A MERSEY MP yesterday accused a French-owned energy firm of stinging British families with sky-high prices rises – to keep bills down on the other side of the Channel.

Birkenhead MP Frank Field launched a furious attack on EDF Energy after it hiked gas tariffs in Britain by 22% and electricity charges by 17%.

In sharp contrast, price rises in France have been strictly capped at just 5% – something that is possible because EDF is state-owned.

Now Mr Field has accused the company of subsidising its French operations by pushing up British bills more than otherwise necessary, plunging more families into fuel poverty.

He is among up to 100 Labour backbenchers urging Gordon Brown to impose a windfall tax on the energy giants to cut the bills of the poorest and fund a desperately-needed home insulation programme.

Yesterday, Downing Street said such a tax had not been ruled out in an announcement expected next week, amid claims that it was giving in to "blackmail" from the energy companies.

Mr Field said: "It’s quite clear British consumers are subsidising French consumers, or that the company is making extraordinary windfall profits.

"What is the regulator doing when a company operating in two countries can have two such distinct polices – and policies to the disadvantage of British consumers."

But EDF hit back, accusing Mr Field of getting his facts wrong. It insisted both markets were entirely separate – with no cross- subsidy – and that French bills were lower because fuel came from nuclear power.

A spokesman said: "By contrast, Britain is heavily reliant on fossil fuels for its electricity. With nuclear, France is largely insulated from soaring fossil fuel prices while Britain is hugely exposed.

"We take great pride in our leadership record in the UK in helping to protect our most vulnerable customers during this period of rising prices." The row came as Liberal Democrat leader Nick Clegg said the Government’s long-trailed package to ease the pain of higher fuel bills had been delayed from this week because of clashes with the energy giants.

Insisting they should be taxed on £9bn windfall profits, Mr Clegg said: "It looks as if the government has surrendered to blackmail by the big foreign-owned energy firms."

A No.10 spokesman said: "Our position has not changed. We want to work with the energy companies, but we rule nothing out."

Among the near-100 Labour MPs demanding a windfall tax are Peter Kilfoyle (Walton), as well as West Derby Labour candidate Stephen Twigg.

Supporters say the big energy providers have enjoyed an astonishing leap in profits from £550m in 2003 to more than £3bn now – while spending £150m on cutting fuel poverty.

But critics of such a tax insist it would stop the energy giants investing billions in new renewable energy sources