There have been reports, in other media, that the DUP had been in discussions with the Conservatives as well, but had been snubbed – partly because of some DUP members' views on homosexuality and the DUP vote with Gordon Brown on 42-day terrorist detention.

Indeed, DUP leader Peter Robinson met with Tory leader David Cameron as late as Tuesday.

News Letter sources said there "was some substance" to suggestions the DUP and Conservatives have talked about closer co-operation.

But at a Press conference yesterday, Conservative shadow Northern Ireland Secretary Owen Paterson suggested the DUP-Tory talks were not of the same coalition nature as the UUP discussions (which have been taking place for almost a year).

DUP deputy leader Nigel Dodds indicated that the UUP could find itself compromised by getting into bed with the Tories.

He said: "The DUP is first and foremost a party which seeks to defend and promote the Union. We believe that the interests of the Union are best served by being free to speak and vote at all times in accordance with that overriding objective... not the preferences of another political party."

Mr Dodds insisted the DUP has maintained good relations with the Conservatives – despite the 42-day detention row – but he noted the Tories and Labour had, in the past, "adopted policies or promoted measures which have been detrimental to the Union or against the interests of unionists in Northern Ireland".

The DUP would, he said, maintain links to the Tories and Labour but with the prospect of a hung Parliament stronger than ever, it would use its bloc of nine MPs and strong position to negotiate on behalf of Northern Ireland and the unionist cause.

Meanwhile, any problems between the Tories and the DUP were not on show yesterday when DUP MP David Simpson and Mr Paterson met at Dan Winter's Cottage on the Diamond site, near Loughgall.

The Tory said he would continue to have close contacts with the DUP.