OVERVIEW:BRIAN COWEN and Gordon Brown have pledged to work "diligently and assiduously" to assist and promote economic progress in Northern Ireland, although the British prime minister stubbornly resisted calls to cut corporation tax in the North.

The issue of harmonising the tax between the Republic and the North to practically assist investment in Northern Ireland was raised a number of times with Mr Brown at the US-NI investment conference in Belfast yesterday, with publisher Sir Anthony O'Reilly pushing strongly for such a move.

He accused the British government of "remaining stone deaf" to reducing the British rate of 28 per cent to the Irish rate of 12.5 per cent. Such harmonisation was justifiable in Northern Ireland because it was "emerging from 35 years of conflict".

He said the British government's Varney report, rejecting the harmonisation, "showed no understanding whatsoever of what makes business here tick".

Mr Brown, while pledging support for economic development, again refused to budge on the issue of harmonisation. He argued that other allowances and incentives in part compensated for the big differential in corporation tax, and that the North was an attractive place for the 120 visiting American executives to invest.

Mr Cowen and Mr Brown, who met three times yesterday - at Belfast City Airport, at Stormont and at Hillsborough Castle - spoke of their joint determination to deliver more "jobs, prosperity, security and a great future" for Northern Ireland.

The prime minister, in what he pitched as a gesture of practical assistance, said that he was raising from £1 billion to £2.2 billion the amount of money the Northern Executive can retain for re-investment from selling off assets.

Hitherto, any sums raised over £1 billion and over three years went into the central British exchequer.

Northern Executive ministers, however, are understood to be dismissive of this move, although, to quote a senior Stormont source, no overt criticism was voiced because it would have been viewed as "bad manners on such a day".

The same source said that it would not be feasible or realistic to release onto the market, in the current financial climate, assets on such a scale.

The two leaders at Parliament Buildings, Stormont spoke privately to the 120 US business chiefs who are visiting Northern Ireland for the conference, arguing of the practical benefits of investing in the North.

Mr Brown told reporters that yesterday was "an historic day of opportunity for Northern Ireland". He congratulated Mr Cowen on his appointment as Taoiseach and said that in the future the British-Irish relationship would be "stronger than ever".

"Just as Tony Blair and Bertie Ahern worked last year to move things forward so Brian Cowen and I will work together to move things forward in the next year," he added.

Mr Cowen said the Government was determined to do all in its power to boost the economic prospects of Northern Ireland. "In all, the investment here by the Government under our National Development Plan is likely to comfortably exceed $1 billion. That's the measure of our commitment and our confidence as we start the process which will deepen and increase in the years ahead under my premiership," he said during a press conference.

Mr Cowen said he wanted to "foster for our mutual benefit the logic of the island economy here in Ireland". He referred a number of times to the benefit of developing North-South relationships and working to an "island economy".

"The prime minister and I are equally determined to do everything we can to bring the prestige of our respective offices to this process to ensure that people see that Northern Ireland is very much open for business," he said.

"I believe that all of us will see significant projects coming to Northern Ireland which will create hundreds, indeed thousands, of jobs in the years to come," he added.

Mr Cowen appealed directly to the US executives "to be part of something truly historic, and to play a personally memorable and economic role" in the development of Northern Ireland.

"When the history is written of the early 21st century I believe that the progress here will rank as one of the most remarkable successes of our time," added the Taoiseach.

During the conference the mayor of New York city, Michael Bloomberg, said he envisaged Belfast developing as a major financial services centre.

"The Dublin, Belfast and London triangle could be one of the most competitive hubs in the world if the political situation continues to improve," he said.