An extraordinary attempt to block Britain leaving the EU has been revealed after a European Commission staff member sent a letter to all MPs demanding they vote to prevent Brexit.

Tory MP Henry Smith highlighted the missive - sent from a British citizen working for the EU in Brussels - and has sent a copy of the letter to MailOnline, which you can read in full below.

The employee says politicians should not support invoking Article 50 of the Lisbon Treaty despite the clear Leave vote in the referendum.

She wrote a list of remarkable claims on why MPs should block last month's Brexit vote.

Among the most outlandish was a claim the referendum was 'not an exercise in real democracy' - despite a record 33.5million people turning out to vote.

She also told MPs to reject the Brexit result - backed by 52 per cent to 48 - because the decision was too 'complex' for the 'uninformed' electorate.

Tory MP Henry Smith (pictured) was sent an extraordinary letter from an EU Commission staff member demanding he votes to prevent Britain cutting ties with Brussels

But the EU employee - a British citizen now living in Brussels who Mr Smith refused to name - did admit: 'I'm aware that you may see me as a turkey trying to overturn a vote for Christmas.'

Mr Smith, MP for Crawley, told MailOnline it was 'breathtaking' that an employee working for the 'remote' European Commission should 'seek to interfere with a British democratic decision'.

The lobbying emerged amid a major constitutional row over whether the Prime Minister can trigger Article 50 - the formal mechanism for exiting the EU - or parliament has to approve the move.

Top law firm Mishcon de Reya has threatened to take the government to court if it does not call a Commons vote before activating the Treaty.

If successful, the bid could hand MPs - three quarters of whom supported Remain - the power to delay our departure and control the terms.

David Cameron has insisted it will be the duty of his successor to trigger the mechanism after he resigning in the wake of the referendum's bombshell Leave victory.

Home Secretary Theresa May, the favourite to take over as PM, and Justice Secretary Michael Gove have suggested they would not push ahead with the move this year.

But Andrea Leadsom, who supported Brexit, has insisted Article 50 should be activated as soon as possible to give investors and the public certainty.

Tory MP Henry Smith, who supported Leave in the referendum, expressed his amazement at the letter

Today the Cabinet minister Oliver Letwin said there were 'conflicting views' over whether Article 50 can be invoked under prerogative powers or required parliamentary approval.

Mr Letwin told the foreign affairs committee: 'It is entirely a matter for the new administration to take how to conduct the entire negotiations, and obviously part of that decision is about when to trigger Article 50.'

'I am advised that the Government lawyers' view is that it clearly is a prerogative power. No doubt that will be heard in court.'

Mr Letwin said the issue was 'academic' because the withdrawal process will also involve either repealing or amending the 1972 European Communities Act, which will require debates and votes in both Houses of Parliament.

The letter - sent by an EU employee but in a personal capacity - sent to Mr Smith is understood to have been sent to a number of MPs amid growing efforts by pro-EU campaigners to overturn last month's Brexit vote.

It also exposes that the efforts come from the heart of the European Commission. The full letter can be read below.

Henry Smith, MP for Crawley, told MailOnline it was 'breathtaking' that an employee working for the 'remote' European Commission should 'seek to interfere with a British democratic decision'

The EU Commission employee, who has remained anonymous due to data protection laws, wrote a list of remarkable claims in a letter to Henry Smith (pictured right with David Cameron) on why MPs should block last month's Brexit vote

Speaking to MailOnline this morning, Mr Smith said: 'I think it's quite breath-taking that a European Commission employee should seek to call for the overturning of the EU referendum result.

'The whole establishment was on the side of Remain, extending to spending over £9million sending a leaflet to every household.

'This was a clear vote and needs to be followed through on and the wishes of the majority of British people need to be followed through on.

'It's particularly rich coming from the remote EU Commission that they are seeking to interfere with a British democratic decision.'

CONSTITUTIONAL ROW THREATENS TO DERAIL BREXIT MOVE Today's revelation of EU Commission staff personally lobbying MPs to oppose a move to stop the Government triggering Article 50 emerged amid a major constitutional row over who has the power to start the formal process of leaving the EU. Top law firm Mishcon de Reya has threatened to take the government to court if it does not call a Commons vote before activating the key clause in the Lisbon Treaty that sets out the process for cutting ties with Brussels. If successful, the bid could hand MPs - three quarters of whom supported Remain - the power to delay our departure and control the terms. The debate over who triggers Article 50 of the Lisbon Treaty may seem technical - but it could be crucial to our future relationship with the EU. It had been widely assumed that the Prime Minister would be able to notify fellow leaders of our intention to leave at a Brussels summit. Many believe the premier can do that under so-called royal prerogative - the same powers that allow him to declare war on the country's behalf. But the Mischon action challenges that notion, arguing that in fact only parliament can consent to Article 50 being invoked. The lawyers say a Commons vote would be required - and as only a quarter of MPs supported Brexit they may not willingly comply. Pro-EU politicians could gang up to delay the process indefinitely on the grounds that the country is not ready to start leaving. Or they could use the vote as leverage to demand the government negotiates terms that keep us tied in as closely as possible to the EU. If whoever takes over as PM chooses to press on without a vote, there could well be a full-on court battle and a constitutional crisis, which risks paralysing the country at a key moment. Advertisement

Posting on Twitter, Mr Smith - who backed Leave in the referendum campaign said: 'Seriously, have just received email from EU Commission employee located in Brussels demanding as MP I vote to cancel UK referendum!'

He then posted an image of the letter, without the name of the individual who sent it.

'I am writing to you to ask you to ensure with your fellow MPs that the house will reject any motion to invoke Article 50 of the Treaty of Lisbon to terminate the UK's membership of the EU that the government may bring before it,' the letter said.

It argues that the 'referendum is not legally binding on Parliament as a matter of constitutional law'.

'A matter of such fundamental importance should not be decided on a bare majority. (By comparison, under company law, the constitution of a company can only be changed with a special majority - usually 75 per cent).

'It cannot be right that the country's opinion on an issue of such gravity should be decided on such a narrow margin. Although the turnout was high for a UK election, nevertheless millions did not vote.'

The letter went on to argue that the 'reasons for holding the referendum in the first place were flawed. The correspondent claims the ballot was 'effectively held for domestic party political reasons, yet the outcome will shape Britain's and Europe's future for years to come.'

It also insists that the electorate was not qualified to decide on 'such complex issues' and people 'felt they were uninformed'.

'The vote was won by a less than 4 per cent margin, yet over a third of voters felt ill equipped to make a decision.'

The letter has enraged MPs who have fought for years for Britain to leave the EU.

Leading Eurosceptic MP Peter Bone told MailOnline: 'It shows the actual attitude of people in the EU elite.

'As we know, whenever a referendum goes against the wishes of the EU, they immediately set about undermining it, hoping to get a second referendum.

'And we've seen that happening in the past. Because what they've got here is a huge vote of the British people they realise they can't get a second referendum but try and get it blocked in Parliament.

'But we of course know there is a majority [of MPs} in favour of remaining in the EU. 'My view is that if MPs try to block the wishes of the British people there would be total uproar and I expect whoever was in government would be out of office very quickly.

'My message to the EU is: Stop meddling in British affairs, the people of the UK has spoken; respect the decision and get on with it.'

Mr Smith, MP for Crawley, posted a copy of the first page of the letter on Twitter, without the name of the person who wrote it

Yesterday's manoeuvre by Mishcon de Reya raises the prospect that there would have to be a vote in the Commons before proceeding with Article 50 - potentially taking the decision out of the hands of the PM.

Some MPs who campaigned for Remain have stressed the referendum was advisory and suggested the impact should be minimised or even ignored.

Among up to a thousand business figures and academics thought to be involved in the Mishcon bid is entrepreneur Alex Chesterman.

Mr Chesterman, who founded the Zoopla property site, circulated an email to other business figures urging them support the move to ' that this once in a generation issue is handled properly under UK law', according to the Guido Fawkes blog.

The legal firm is adamant that Parliament must have its say, and has been in correspondence with government counterparts to seek assurance over the process and plan to pursue it through the courts if they are not satisfied.

Kasra Nouroozi, a Mishcon de Reya partner, said: 'We must ensure that the Government follows the correct process to have legal certainty and protect the UK Constitution and the sovereignty of Parliament in these unprecedented circumstances.

'The result of the Referendum is not in doubt, but we need a process that follows UK law to enact it.

'The outcome of the referendum itself is not legally binding and for the current or future prime minister to invoke Article 50 without the approval of Parliament is unlawful.

'We must make sure this is done properly for the benefit of all UK citizens. Article 50 simply cannot be invoked without a full debate and vote in Parliament.

'Everyone in Britain needs the Government to apply the correct constitutional process and allow Parliament to fulfil its democratic duty which is to take into account the results of the referendum along with other factors and make the ultimate decision.'