Britain's Business Secretary Lord Mandelson said the country was heading for a "cliffhanger" result after an exit poll pointed to a hung parliament.

Lord Mandelson said: "Of course, many people have turned away from the Labour Party but what they haven't done is to fly into the arms of David Cameron's Tories."

Asked if Labour would do a deal to stay in power, he told BBC News: "The constitutional conventions are very clear.

"The rules are that if it's a hung parliament, it's not the party with the largest number of seats that has first go - it's the sitting government."

Pressed again on whether he would do a deal with the Lib Dems to hold on to power, he said: "I have no problem in principle in trying to supply this country with a strong and stable government."

Commenting on the joint BBC/ITV News/Sky News poll, he said it looked as if the country was heading for a "cliffhanger of a result".

A senior Tory source said: "If true, this poll is a decisive rejection of the Labour Government.

"The Conservatives would be gaining the most seats for 80 years and see the biggest swing for 80 years. We will do what we need to do to provide stable government for Britain."

Shadow work and pensions secretary Theresa May told BBC News: "If it is correct, I think what it does show is a clear rejection of Gordon Brown.

"I think it shows that Labour would have lost their legitimacy to govern."

Conservative Party chairman Eric Pickles told ITV News that the Tories would "of course" seek to offer stable government in a hung parliament if that was what the public chose.

And he added: "My good instinct is that your exit poll is probably wrong but if it's right, Labour have lost the election, they've lost any legitimacy.

"There isn't a possibility of them being able to put together an administration that would be able to last the lifetime of a parliament."