A home energy saving scheme is failing to help Britain' poorest who cannot afford their heating bills.

The government's spending watchdog warned on Wednesday that the £150 million Warm Front scheme, which was created to improve energy efficiency in households at risk from fuel poverty, could be made more effective.

The National Audit Office concluded that the scheme had helped 300,000 households save on average £150 but warned it is not reaching those in greatest need.

Warm Front offers energy efficiency and heating measures that are not having as much impact as they might, the watchdog also concluded.

The scheme, which is run by DEFRA, is a key part of the government's fuel poverty strategy which has been set a target of alleviating the problems in Britain's most vulnerable homes by 2010.

It has achieved a high level of customer satisfaction and attracted few complaints but the watchdog called for better targeting of resources, warning the energy efficiency of the claimant's home is not taken account.

"The Warm Front scheme makes a difference to the warmth and fuel bills of so many people," said NAO chief Sir John Bourn.

"However, more could be done to help those households most in need by reducing expenditure on measures which have limited impact on fuel costs and on homes which are already energy efficient.

"And funds should be redirected to better assist, for example, those in 'hard to treat' homes such as those not connected to mains gas or without cavity walls."