A Tory minister suggested that wealthy pensioners could give their taxpayer-funded Winter Fuel Allowance to charity just hours before David Cameron pledged to guarantee the payments for another five years.

The allowances, alongside and free television licences, would be shielded from cuts if the Tories win in May the Prime Minister said in a repeat of his promise before the 2010 General Election.

Labour and the Liberal Democrats have said that they want to remove the benefits from some of the richest pensioners.

But Mr Cameron rejected that move, saying the money was what older people "deserved".

But there was controversy when a Tory minister suggested that those who did not need the state handout could give the money away - to the charity of their choice.

On the BBC's Today programme Work and Pensions minister Minister Mark Harper said: "People are perfectly entitled in a free society when they get money to do whatever they want with their own money. And I have heard things like. for example, people have given the money to charity."

Pressed if he thought that was a "good idea", he said: "It is not for ministers to tell people how they should spend their own money".

Mr Cameron said it was "wrong" to call the perks a luxury.

"Say that to the older woman who can keep warm tonight on this cold February evening, because she's been given the money to heat her home," he said.

The remarks came as Ukip pledged to force migrants to buy health insurance or face being refused entry to the UK.

The policy was a centrepiece of the party's plans for the NHS - as it tries to appeal to Labour voters in constituencies in the south of England where it is facing a tough battle to win seats.

Ukip also said it would increase spending on dementia, as leader Nigel Farage attempted to distance himself from comments he made in 2012 calling for a fully insurance-based NHS.

Meanwhile, David Cameron and Ed Miliband will go head to head exactly a week before the May 7 general election, if the planned television debates go ahead.

Broadcasters held an FA-cup style draw to decide the order in which they should be held.

The result means the two 7-party debates, which will also feature the SNP, Ukip and the Greens, but not the DUP, will take place earlier in the campaign.

Labour leader Ed Miliband has written to David Cameron, who has said he does not ant debates so close to vote day, to call on him to say once and for all whether or not he would take part,.

The Lib Dems said that they had a number of "gripes", including that they will be excluded from the last debate and unable to defend their record in government, but said they were committed to taking part.

Meanwhile, a new poll by Tory peer Lord Ashcroft poll shows Labour pulling ahead of the Conservatives.

The party was up 1 percentage points to 36 per cent, with the Conservatives on 32 per cent, Lib Dems 7 per cent, UKIP 11 per cent, Greens 8 per cent

The Ukip share was the lowest ever in an Ashcroft poll.