Tory MPs have drawn up a new law that would see any British citizen who undermines Government negotiations abroad face jail.

The Mail on Sunday can reveal the backbench push comes in the wake of angry claims by Boris Johnson's No 10 officials that anti-Brexit members of Parliament had worked with EU countries to wreck the UK's exit negotiations.

Now, MPs from the European Research Group of hardline Brexiteers want to make it a crime for British citizens to undermine official Government negotiations by launching shadow talks or inviting foreign help in drafting domestic legislation.

Last month, Downing Street launched an investigation into alleged links between foreign governments and the MPs behind the amendment which last night forced the Government to attempt to seek another Brexit extension.

Sources said No 10 took the unprecedented action after officials received intelligence that the MPs, including former Cabinet Minister Oliver Letwin, had received help drafting the Bill from members of the French Government and the EU.

Sources said No 10 took the unprecedented action after officials received intelligence that the MPs, including former Cabinet Minister Oliver Letwin (pictured), had received help drafting the Bill from members of the French Government and the EU

It was even suggested by senior sources that Mr Letwin had agreed the extension date of January 31 in the first Benn Act with sources at the French Embassy in London.

The claims were denied by the rebels, but they did not deny having meetings with Eurocrats and foreign diplomats.

Former Prime Minister Tony Blair has also been accused of undermining Britain's negotiations by privately lobbying EU figures to delay Brexit so the UK can hold a second referendum.

The new Bill's likely sponsor, West Yorkshire MP Andrea Jenkyns, said last night: 'The Prime Minister performed admirably to return from Brussels with the deal he did.

'But the reality is, he was sent to the EU with one arm tied behind his back while his opponents have shuttled back and forth attempting to have the EU kick his legs out from under him.'

Brexit-backing Ms Jenkyns added: 'The events of the last few months confirm that the UK must join its international allies and institute laws to ban such actions that jeopardise British statecraft.'

The new Bill's likely sponsor, West Yorkshire MP Andrea Jenkyns (pictured), said last night: 'The Prime Minister performed admirably to return from Brussels with the deal he did'

The group will use a little-known Commons device called a Presentation Bill, a type of private member's bill, in an attempt to kick-start the new law.

Last night Home Office sources said Home Secretary Priti Patel would be fully briefed on the proposed legislation and study the feasibility of a clampdown.

Ms Patel was a leading light of the ERG and is understood to share the widespread anger within the Government at alleged attempts by rebel Tories to hamper negotiations.

The plan for a new law is understood to be based on a study by the Henry Jackson Society think-tank to replicate the Logan Act, a similar piece of legislation in the USA. Their law is named after pacifist Dr George Logan who entered into unauthorised negotiations with France in 1798 in a bid to avert conflict with the United States.

Only two people have ever been indicted on charges of violating the US Act, both in the 19th Century, and neither were convicted. The maximum penalty for breaking the new law would replicate US law at three years' imprisonment.

Last night, James Rogers, director of the Global Britain Programme at the Henry Jackson Society, said: 'In the past, Britain has not needed an American-style Logan Act as well-observed convention left diplomacy to authorised government ministers.

'The recent rise of 'shadow negotiators', both with the EU and with foreign governments beyond, has destroyed that convention and risks undermining the national interest.

'Therefore, very serious consideration is likely to be given to new laws to deter unauthorised diplomatic activity with foreign actors with whom the government is in negotiation and disagreement.'