When Brendan Butler formed the Irish El Salvador Support Committee 21 years ago there was only one other international campaign group around. "There were the Chileans and there was us," he recalls.

Today, almost 30 such campaigns can be found. From Nicaragua and Sudan to Liberia and Kurdistan, there is barely a trouble spot in the world that is not now represented by some sort of Irish solidarity group.

The growth can be attributed to a more global outlook in Irish society, or can be seen as a reflection of a greater cultural mix here. Either way, most if not all these groups depend on a small number of dedicated campaigners, people who are willing to toil, often in solitude, writing letters to distant governments and mounting lonely pickets outside embassy gates. All this is unpaid, and often they have to bear the cost of their campaigns personally.

They are people like Mr Butler, a deputy school principal from Swords in Co Dublin who, as well as running the El Salvador committee and establishing Latin America Week, the annual awareness-raising event, has been the driving force behind recent protest groups against Russian war crimes in Chechnya and human rights abuses in Algeria.

Asked why he does it, his reply is typical of such campaigners. "No one else was doing anything on the issue. It was just being ignored," he says of Algeria. "And that shocked me."

That was two years ago when reports were growing of attacks by Algerian government troops against the Islamic opposition, in which hundreds of civilians were killed. "We put a letter in The Irish Times, inviting people to a protest at the Department of Foreign Affairs. About 200 people turned up and the campaign was born."

Mr Anthony O'Brien, another veteran of the campaigning sector - in his case the Tibet Support Group - has a similar story. "It was a Dispatches documentary in September 1988. They had filmed secretly inside the territory and the images were horrific."

The following day he rang Amnesty International to find out whether there were other people who felt as strongly as he did about the issue and, soon after, a group was formed.

A potter and artist from Ballsbridge in Dublin, Mr O'Brien lives, ironically, just 100 yards from the Chinese embassy on Ailesbury Road. "I think they think I'm completely mad," he says of the government officials working there.

Like other campaigners, he believes the job has become more challenging in recent years. Groups have had to adapt their messages, become more professional and a little less militant, partly due to a shift in international politics away from condemnation to something called "constructive engagement", a euphemism, in the view of many campaigners, for letting rogue states off the hook.

Another factor is the booming economy, says Mr Joe Murray, co-ordinator of Afri, an agency through which a number of campaigns, such as those on West Papua, and Ogoniland in Nigeria, operate. "It is a much more hostile environment now than in the 70s and 80s. The boom in wealth has numbed people's sensitivities towards issues of justice. People just don't see the relevance. They don't even want to make the connection."

The change is most notable in young people, he says. "Students now are only part-time students. They're primarily workers, and that time which used to be available for campaigning or charity work is no longer available." But Mr Butler describes this as a "two-edged sword". Young people are busier but, equally, some campaign groups have been slow to adapt to their requirements.

"We used to come in at eight and nine at night to have meetings in UCD and Trinity but people won't hang around until then any more. They want lunchtime meetings instead. There is also no point in having someone talking away for 20 minutes about Algeria. You have to compete with the media of the 21st century and use more audio-visual materials."

Proof of young people's involvement can be found in the One World Society in Trinity College Dublin, a group which can mobilise hundreds of students for street demonstrations. Ms Eileen Seymour (32), who joined Burma Action Ireland as an ordinary member three years ago, has become chairwoman. A physicist in the nuclear medicine department of St Vincent's Hospital, Dublin, she became involved in human rights campaigning after a working holiday in Australia and Asia. On her travels, she managed to cross the border illegally into Burma and visit a village camp run by the Burmese opposition.

"They had set up their own school and were teaching little kids. It made a very strong impression on me." Since they began arriving here in greater numbers, asylum-seekers and refugees have also become heavily involved in human rights and solidarity groups linked to their native lands.

Mr Khalid Ibrahim of the Iraqi Human Rights Organisation in Ireland, which is campaigning not just against Saddam Hussein's dictatorial regime but also against UN sanctions which contribute to the deaths of up to 6,000 Iraqi children a month, is one such person. A Kurd who fled Iraq 10 years ago, taking refuge in Syria and Russia before settling here and gaining refugee status three years ago, he can be found every Saturday on College Green in Dublin gathering signatures against the trade embargo.

"We have been doing this for four months now and have got thousands of signatures. How long will we be here? I don't know. In Britain, the campaign said they would do the same thing for a year and now they are going four years."

That is one thing all campaigners agree on: they can never say when it will end.

Just look at Mr Tom Hyland, co-ordinator of the East Timor Ireland Solidarity Campaign who, after almost 10 years of often heartbreaking toil, saw East Timor finally gain its freedom last October. Yet thoughts of retirement are far from his mind.

The former Dublin bus driver is working in East Timor, helping locals establish grassroots organisations in the employment, agriculture, health and education sectors. "It's not enough for us to go away yet," he says. "There is a long way to go before people here are really free."

"Over the past 12 years one has gone through these cycles of excitement, elation, burnout and exhaustion," Mr Anthony O'Brien says. "You go from being very active to very depressed, and you realise nothing is going to change overnight. What it comes down to in the end is just trying to keep the issue alive."