MPs warn Brown he faces losing support after £100 fuel voucher plan backfires

One of his closest allies, former Treasury minister Geoffrey Robinson, fuelled party unrest by backing calls to make suppliers share their profits.

Downing Street allowed speculation to build last month that low-income families could get vouchers worth as much as £100 to help with their fuel bills this winter.

PM Gordon Brown ruled out a one-off payment to help with fuel bills during a keynote speech at the Glasgow Hilton Hotel on Thursday

Fabian Hamilton says Labour faces losing support from backbench MPs

It was supposed to be part of a package of energy measures unveiled next week as part of Mr Brown's autumn fightback.

But the Prime Minister confirmed on Thursday that he had ruled out any short-term 'gimmicks' and would instead focus on improving home energy efficiency.

Many MPs and trades unions saw this as a climbdown, pointing to the bumper profits enjoyed by energy firms as a result of higher fuel prices.

Fabian Hamilton, Labour MP for Leeds North East, said more than 100 MPs in the party had wanted a windfall tax.

'The consequences for Gordon Brown and the government could be very serious indeed,' he added.

Mr Robinson's intervention caused a stir because he is a long-serving ally of the Prime Minister. He was also an architect of Labour's flagship windfall tax in 1998.

He told Sky News: 'What we are looking for is meaningful contributions in these extremely difficult circumstances.

'I believe these energy companies can't be allowed simply to pass on these huge cost increases that they are getting without doing anything themselves. They have got to get their fingers out.'

He added: 'Let's be tough with these energy companies. Gordon Brown shouldn't think that the way out of his popularity problem is to do things that are irresponsible. He's got to be very hard-headed and strong.'

The row capped a bad week for Mr Brown, after the start of his relaunch was marred by Chancellor Alistair Darling's dire warnings about the economy.

A slump in the pound followed, and then former minister Charles Clarke called for him to 'go with honour'.

The Prime Minister's official spokesman said that discussions with the energy companies were continuing. He defended the Government's approach, insisting that energy efficiency measures were the best way of cutting bills permanently.

'The focus of the discussions with the energy companies is on how we can reduce people's bills not simply for one year but every year,' he said. 'This is the most effective and sustainable way to reduce energy bills in the long-term.'