The Tories have branded the Benefits Agency "incompetent" for allowing the bungle to happen.

But the government says the error accounted for only a small proportion of all the payments made.

Last winter, the handouts were sent to more than 10m pensioners, their bank accounts or issued to post offices for collection.

But because it was the first time such an exercise had ever been undertaken, some payments were sent to pensioners who had moved house or into nursing homes.

"Mistake regrettable"

Pensions Minister John Denham described the incident as "regrettable" but added: "It is a tiny proportion of the 10m payments which were made to pensioners in 7m households."

He was responding at Commons question time to Tory John Bercow (Buckingham), who said: "Can you tell the House how many cheques for winter fuel payments were sent out in error, what the cost of that error was and what proportion of that unwarranted cost has already been written off by your incompetent department?"

The minister replied that he would write to Mr Bercow with the exact figures.

But he believed about 10,000 payments were made which were not in accordance with the legislation. It was regrettable, he said.

He added: "With regard to recovery, each case is being treated on its individual merits and that is obviously the right way for us to proceed."