EU exit '˜will trigger rise in bills'

She will point to figures suggesting that being outside the EU would add £500 million a year to the cost of energy.

Her speech is the latest salvo in the Government’s attempt to win a ‘remain’ vote in June’s referendum on EU membership.

Ms Rudd will say: “The UK’s membership of the European Union has helped keep our energy bills down.

“If we left the European Internal Market, we’d get a massive electric shock because UK energy costs are likely to rocket by at least half a billion pounds a year – the equivalent of British bills going up by around one and a half million pounds each and every day.”

Ms Rudd will warn the UK is set to remain dependent on overseas energy even if it develops shale gas reserves through fracking and leaving the EU would weaken the country’s hand when dealing with countries like Russia.

She will say: “We can’t let our energy security be hijacked as a political pawn to bring Europe to its knees. By working together in the European Union each member state can stop this becoming a reality.

“As a bloc of 500m people, we have the power to force Putin’s hand. We can coordinate our response to a crisis. We can use the power of the internal market to source gas from elsewhere. We can drive down the price of imports, as has happened recently in Eastern Europe.

“To put it plainly - when it comes to Russian gas, united we stand, divided we fall.”

Ms Rudd is likely to face allegations from ‘leave’ campaign groups that her warning is the latest chapter in what they have described as the Government’s “project fear”.

Indeed, the study commissioned by National Grid which is the source of the £500 million figure goes on to say that “most of these impacts could be effectively mitigated” if the UK was allowed to remain in the European internal energy market.

Defying criticism over the use of the Brussels terror attacks to make their case, Arron Banks, founder of the Leave.EU campaign. yesterday claimed EU membership was leaving the UK vulnerable to attack.

He said: “There’s virtually nothing we can do to stop every Islamist sympathiser in Molenbeek from setting up shop in the UK if they so choose, provided they can flash an EU passport on their way in. Many of them are already EU citizens anyway.”

Mr Banks added: “Brussels, the so-called capital of the EU, has taken the grand experiment in state-sponsored multiculturalism and tested it to destruction. The ghettos and extremism are proof this doesn’t work.

“An American politician once said that ‘immigration without assimilation equals invasion’ – and he was right.”

London mayor and ‘leave’ campaigner Boris Johnson clashed with Treasury Select Committee Andrew Tyrie yeseterday as he gave evidence to MPs.

Mr Tyrie accused him of offering “a very partial, busking, humoresque approach to a very serious question for the UK”.

Mr Johnson responded: “I’m glad you say that, because some of my views have been traduced. I’m grateful to you for the opportunity to set straight some of the gross misrepresentations that have been made.”

The mayor also rejected claims that Britain could face a long period of uncertainty after leaving the EU.