Kofi Annan came mainly to pay tribute to Ireland's long involvement in UN peacekeeping, but conflict was never far from his mind. On the day he arrived, the New York Times published an article by him responding to hostile press criticism he has received recently in the US.

Shortly after his arrival, he rang the Yugoslav Foreign Minister to persuade him to allow international investigation of the latest massacre of Kosovo civilians.

His voice must be the gentlest in public life anywhere. He is often referred to as quiet-spoken, but this exaggerates the volume at which the Ghanaian spoke in a suite in a Dublin hotel this week.

Mindful of where he was, Mr Annan, a former head of the UN's peacekeeping department, volunteered unsolicited praise for Ireland's contribution over the years.

"The men and women of Ireland have made a major contribution to peacekeeping," he said. "They are well-trained, they have the right temperament and they have done extremely well. They are highly respected and popular amongst other nations."

The nature of UN peacekeeping, however, has changed in recent years, with major missions, such as Sfor (Stabilisation Force) in former Yugoslavia, being organised and commanded by NATO rather than the UN itself. With the UN now encouraging regional organisations such as NATO to organise UN-mandated peacekeeping operations within their own region, can Ireland continue its commitment to peacekeeping while having nothing to do with NATO?

The decision on involvement with NATO "would be a choice that Ireland would have to make, but as far as the UN is concerned there is no impediment" to future Irish participation in traditional peacekeeping operations. "We should be able to continue to work with you in the way we always have."

He says the number of peacekeeping troops under direct UN command has fallen dramatically.

"At its peak we had about 80,000 people deployed in about 17 operations. We are now down to about 14,000, but the interesting thing is that the number of peacekeepers globally hasn't dropped all that much. In the way you refer to, it has been diversified with 30,000 people in NATO-led Sfor in Bosnia year; Russian-led CIS troops in Georgia and Tajikistan; the west African forces, Ecomog, in Nigeria and Sierra Leone. If you add the numbers up, they haven't dropped that drastically."

While the regional organisations are running many UN-mandated peacekeeping operations, there is still a need for the more traditional UN missions. "Some of these forces such as NATO and CIS troops cannot operate outside their own region, and so if we have a major crisis which the world decides to do something about, it is to the UN that they will turn."

Whoever actually commands the peacekeeping forces, he says, international peacekeeping is here to stay. "I think we shouldn't write off peacekeeping yet. When we look around this messy world we live in there is going to be a continuing need for their services."

He also has praise for the other high-profile Irish involvement in the UN: Mary Robinson in her role as High Commissioner for Human Rights. "Mrs Robinson has made a remarkable contribution in a relatively short period," he says. "She has brought leadership, dynamism and ambition to her tasks, and it is a very demanding job."

While Mrs Robinson has alienated regimes in Rwanda, Algeria and elsewhere through her work, Mr Annan suggests that this may be an inevitable consequence of promoting human rights values. "They transcend all borders, and it is wrong for one to argue that it is a western concept being enforced on other regimes," he says.

He is optimistic that the proliferation of means of communication through broadcasting, the Internet and others will reduce the capacity of individual regimes to deny their own peoples' human rights. "We live in a world today where communication and the spread of information is relatively easy. People are in touch and sharing information, and I think governments are realising they will have to engage people and create an environment that will allow people to live their lives and to have choices."

The US and British decision to bomb Iraq recently without seeking explicit UN Security Council approval once again undermined the UN's desire to be seen as the arbiter of international disputes. The US decided to do what it wanted, and Mr Annan, who himself brokered a deal to avoid air strikes last February, could only watch.

The UN's relationship with the US is further complicated by the US owing it about £1 billion (some of this in turn is owed to Ireland for its involvement in peacekeeping missions). The US calls the shots but won't pay the bills.

Asked if the US and Britain had legitimacy for the bombing of Iraq, he answers carefully. "You saw the reaction of certain Security Council members, including some of the permanent members, to that action. They made it clear that they did not consider it as something the council has sanctioned.

"The British and the Americans believe they had authority on the basis of existing resolutions to do this, so the best one can say is that there is a difference of interpretation. The council is now trying to deal with the morning after and see where they go from here. Even though they are at the moment divided I hope they will find common ground."

When invited to express a personal view on whether the US and Britain were right to take their military action, he laughs politely and declines. On whether NATO could take military action against Yugoslavia over Kosovo without a further UN Security Council vote, he also chooses his words carefully.

"We are facing a very difficult situation in Kosovo. I hope that President Milosevic and the Yugoslav leadership will take the interests of their people into consideration, listen to the international community and desist from further escalation.

"Obviously, the most important thing here is the search, as difficult as it is, for a political solution. I hope we will be able to find a way forward without resorting to violence, without resort to the use of force."

Is there an obligation upon NATO to seek specific authorisation from the Security Council before it takes any military action?

"The council as a practice has encouraged all organisations to refer to the council on issues of this nature," he says. Should this practice be continued in the case of possible military action against former Yugoslavia? He laughs politely again and says: "I think I've given you enough there."

The latest controversy in the often bitter relations between some members of the US Congress and the UN concerns allegations that material gathered by the UN weapons inspectors (Unscom) in Iraq was given to US intelligence. The US press reported that Mr Annan had "convincing evidence" of this.

To the question: "Do you believe information gathered by Unscom fell into the hands of the US at any stage?" Mr Annan replies: "I have no specific evidence.

"I know that some press publication said that I had convincing evidence. I have no such evidence. I posed the question to the chairman of Unscom, Mr Butler, who told me firmly that there has been nothing of the sort, and the early American reaction to this also denied any abuse whatsoever.

"Reports and allegations keep coming out that this did happen, but I have no evidence."

He says he had hoped to have made more progress on getting the US Congress to agree to pay the massive bill it owes the UN. The original stated reason for withholding the money was that the UN must reform first. It was certainly an inefficient bureaucracy with overlapping agencies, departments treated like fiefdoms and an under-representation of women in responsible posts. Considerable changes have been implemented, but there is still no sign of the money.

Mr Annan says the UN has "accomplished quite a lot in the area of reform in the last two years. We have organised ourselves in a manner that requires us to focus on our core objectives, which I would define as peace and security, economic and social affairs, economic co-operation, humanitarian affairs and human rights.

"We have reduced our entire staff by about 1,000 positions, we have brought in a new Deputy Secretary-General and we have increased the number of women in senior positions and have appointed able leaders to some of the key positions."

The reality is, however, that many US critics of the UN, particularly those on the political right, object to much more than the body's bureaucracy. Underlying the constant tension is the issue of whether the US can act unilaterally as a global policeman, or whether the other 184 UN member-states can rein it in and subject it to global authority.

"I think the American public supports the idea that the US should pay its debt to the UN," says Mr Annan. "Poll after poll confirms this. I hope that now that the new congress is back, it is one of the issues that will be resolved. The president mentioned it in the State of the Union address.

"I think it is important that it should be resolved because it is damaging to the organisation and it doesn't help the US in that it provokes friends and foes alike. Quite a lot of the money is due to countries that have contributed peacekeepers to the UN operations, including Ireland, and we would want to be able to reimburse them a quickly as we can, and we can only do so once member-states in arrears meet their obligations.

"The UN needs the US but the US also needs the UN."