Taoiseach Enda Kenny has publicly pledged to spend hundreds of millions of pounds to build a controversial road in Northern Ireland.

There have been more than 2,400 objections to the planned £850m A5 road from Londonderry to Aughnacloy, on the Monaghan-Tyrone border.

A public inquiry into the viability of the road opened earlier this month.

Its opponents have branded it a vanity project, a “political road” that will not deliver the promised economic benefits and will “cripple” transport budgets north and south of the border.

But at the annual conference of the Institute for British-Irish Studies in UCD, Mr Kenny said: “The previous government had committed to put money in there and we will honour that commitment.” Former Taoiseach Brian Cowen said last January in Armagh that £400m would be provided to fund the route, as well as the smaller and less expensive 14.4km A8 Belfast to Larne dual carriageway project.

But Friends of the Earth Northern Ireland reacted with surprise to Mr Kenny's announcement yesterday.

Its director, James Orr, said the A5 road was not projected to bring about any increase in traffic to the North West despite its enormous cost.

“Since the public inquiry has started there's even more evidence to suggest it's an ill thought out, vainglorious scheme. At the end of the day, we all know this is a political road,” he said.

Mr Kenny spoke of the Irish government's commitment to the scheme yesterday as part of his first public address on policy towards Northern Ireland.

He said he was personally committed to strong North-South relations due to his year-long stint on the New Ireland Forum in the 1980s.

“The government that I will lead is absolutely committed to protecting all of the gains that have flowed from the Good Friday Agreement and will continue to work in that regard,” he said.

Mr Kenny is due to have his first full meeting with First Minister Peter Robinson and deputy First Minister Martin McGuinness at a meeting of the North-South ministerial council in Farmleigh House in Dublin on June 10.

Last week Regional Development Minister Danny Kennedy said he will wait for the outcome of a public inquiry into the A5 road before making a decision on whether the project will go ahead. The Roads Service has confirmed £35m has already been spent on project development