The Ulster Unionist Party last night agreed to form an electoral pact with the Conservatives.

The deal will initially see the parties run on a joint ticket in Westminster and European elections in Northern Ireland.

Senior UUP officials backed the political alliance during a meeting of the party's executive in Belfast.

Representatives from both parties will now form a joint committee to work out an electoral strategy ahead of new year's European poll.

The parties have still to decide whether the partnership will extend to Assembly and local council elections in the region.

A UUP spokesman said: "The Executive Committee of the UUP has overwhelmingly endorsed the creation of a Conservative and Ulster Unionist Joint Committee to oversee and facilitate co-operation between both parties."

He said the joint committee would: "bring forward proposals on manifesto commitments and the branding of candidates, ensuring that the heritage and appeal of both parties are respected and that the popular appeal to the whole Northern Ireland electorate is maximised."

The committee will produce a report at the end of January.

The UUP spokesman said the arrangement would operate on the basis of consensus between the parties.

The Tories and UUP had been involved in detailed discussions since July when leaders David Cameron and Sir Reg Empey declared hopes of launching a new political movement in the region.

The 80-strong gathering of executive members voted in the favour of the deal, which re-establishes historic links between the parties.

The long-standing association was broken in 1985 when unionists objected to Margaret Thatcher's decision to sign the Anglo Irish Agreement, which gave the Republic of Ireland an advisory role in the governance of Northern Ireland.

The Conservative Party already organises in Northern Ireland, but has been unable to make any political breakthrough.

The UUP has, meanwhile, lost ground to the Democratic Unionist Party (DUP) which has replaced it as the largest party in Northern Ireland.

Mr Cameron and Sir Reg hope a pact could extend Tory influence to a part of the UK where it is currently a minority voice, as well as allowing Northern Ireland voters to have a link to national politics.

The Conservatives have already said an alliance could see an Ulster Unionist handed a seat in any future Tory government.

When the two party leaders announced their hopes of building a new political movement, they formed a working group made up of Conservative and UUP members to discuss options.

At the time Mr Cameron said: "The Conservative Party stands in every part of the United Kingdom. We're the only party that does.

"In a lot of elections we have shrunk back to rather an English base... I'd like to see us establish a new political force in Northern Ireland that is both Conservative and Unionist, that can say to people, look, get beyond the old politics of constitution or orange or green.

"Let's actually have a national political party that can stand up for people on all of the issues they care about."

Ulster Unionists hope close co-operation with the Tories could help revive their fortunes.

Their desire to form an alliance with a bigger UK party is also a challenge to moves by nationalists and republicans to deliver Irish unity.

Sinn Fein already campaigns on an all-Ireland basis and has elected representatives on both sides of the Irish border.

The nationalist SDLP has also sought in recent years to form an alliance with one of the Irish Republic's larger parties, though hopes for a tie-in with the lead party of Government, Fianna Fail, have been interrupted by the economic crises dominating politics.

Last night's decision now paves the way for Mr Cameron to attend the UUP annual conference next month.

However, Democratic Unionist MP David Simpson said the UUP risked splitting the unionist vote if it contested all Westminster seats as part of the pact.

He said a DUP/UUP alliance could oust sitting nationalist and republican MPs in South Belfast and Fermanagh/South-Tyrone.

"The position of the Tory leader could not be more clear," said Mr Simpson.

"He has said that he wants to fight every single Westminster seat in Northern Ireland come the next Westminster election."

Mr Simpson added: "The choice for Sir Reg is very stark indeed. He can either go with Cameron and see four more years of nationalism ensconced in Fermanagh and South Tyrone and South Belfast or he can work with other unionists to see unionism increase its presence in Westminster."