Boris Johnson has strongly denied he told a string of ambassadors he was in favour of free movement of EU workers after Brexit, describing the claims as a ‘total lie’.

In an angry rebuttal, the Foreign Secretary challenged the unnamed diplomats to produce proof he told them at a private lunch that he personally supported open borders with the EU.  And he said he has his own records that prove the claims are wrong.

The row is embarrassing for Mr Johnson, who led the Vote Leave campaign that promised to ‘take back control’ of the UK’s borders.

He championed the case for Brexit despite his long-held pro-immigration views.

Today he said he had told four EU member state ambassadors ‘very clearly’ that immigration had benefited the UK but added that it had got ‘out of control’ and free movement of people must end after Britain cuts ties with Brussels.

The claims about Mr Johnson’s alleged remarks about free movement were made on Sky News, by diplomats who attended a lunch with him. All spoke on condition of anonymity.

One ambassador told Sky: ‘[Boris Johnson] told us he was personally in favour of it, but he said that Britain had been more affected by free movement of people than other EU member states.’

Another said: ‘He [ the Foreign Secretary] did say he was personally in favour of free movement, as it corresponds to his own beliefs. But he said it wasn’t government policy.’

An ambassador for a third country said that he was shocked by the Government’s shambolic diplomacy.

He said: ‘Boris Johnson has been openly telling us that he is personally in favour of free movement.’

And a fourth ambassador said: ‘Yes, he told us at an ambassadors’ luncheon.’

But sources close to Mr Johnson described the remarks as a ‘total lie’.

Responding to the claims during a visit to Rome today, the Foreign Secretary told Sky News: ‘I’m afraid I said absolutely no such thing and as you know perfectly well I’ve been a long-standing supporter of immigration.

‘And what I said very clearly to that group of ambassadors, I think it was at a breakfast, was that immigration had been a good thing for the UK in many respects, but it had got out of control and that we needed to take back control.

‘I think you will find the record reflects that.’

The alleged remarks are hugely sensitive for the Government. Theresa May has repeatedly stated that her priority in the Brexit negotiations is ending free movement.

And they came as a tricky time for the Government, which faced further criticism today over immigration after official figures revealed a new record of 650,000 people came to the UK in the year ending June 2016 following a surge in EU migration.

Asked about Mr Johnson’s alleged remarks, the Prime Minister’s spokeswoman said: ‘I think the Foreign Secretary’s office have responded to those suggestions this morning and made clear that the Foreign Secretary was setting out some views that he has made before about the benefits of immigration to this country, while also making clear that he wants to take back control of immigration.

‘That is the Government’s policy and that is what we will be pursuing in our exit from the EU.’

She added: ‘The Prime Minister has been clear that one of the key objectives of our exit from the European Union will be to take back control of immigration from the EU. As part of that, we have been clear that we want to deliver on the Government’s aim to reduce migration to sustainable levels.’

A spokesman for the Foreign Secretary said: ‘Boris simply said he was pro-immigration but wanted to take back control to limit numbers. He did not say he supported freedom of movement and challenges anyone to show proof that he ever said that.’

Former party leaders Ed Miliband and Nick Clegg attacked Mr Johnson over claims he privately backed freedom of movement, accusing him of treating voters like ‘fools’ and criticising his ‘buffoonery,’ while shadow Brexit secretary Sir Keir Starmer said they showed up the Government’s ‘non-strategy’.

Separately yesterday, Number 10 rejected Mr Johnson’s latest call for an illegal immigrant amnesty.

At a Cabinet committee meeting, the Foreign Secretary repeated his long-standing view that those who have escaped detection for ten years should be allowed to stay.

The idea was immediately dismissed by other ministers, including the Prime Minister. Downing Street said it had ‘no plans’ to follow Mr Johnson’s advice. Details of the meeting were apparently leaked by a fellow minister in an apparent attempt to undermine Mr Johnson.

There is concern at the top of Government that Mr Johnson’s private comments are making it into the public domain. It was recently claimed – falsely – that he arrived at a Cabinet meeting with the wrong papers.

One Westminster source said: ‘This looks like a deliberate attempt to make Boris look isolated and destabilise him – perhaps by somebody who wants the Foreign Secretary job for themselves.’

Mr Johnson first floated the idea of an amnesty during his time as Mayor of London. Mrs May – who was then Home Secretary – said No.

A spokesman for Mr Johnson said: ‘Boris reiterated what he has said publicly before about amnesties, including during the EU referendum campaign.

‘He feels he has a moral responsibility to raise it, as it is what he believes. Any suggestion that there was strong disagreement expressed during the meeting is wrong.’

A Home Office spokesman said: ‘We are not looking afresh at an amnesty for illegal migrants, and will not be’.

Two weeks ago the Foreign Secretary was quoted in a Czech newspaper as saying it was ‘b******s’ that freedom of movement was a fundamental principle of the European Union.

‘It’s something that has been acquired by a series of decisions by the courts,’ he added.

Earlier yesterday Mrs May warned British expats would have been left ‘high and dry’ had she given ground in the row over post-Brexit residency rights.

The Prime Minister has been under enormous pressure to strike a deal with Brussels allowing the almost four million EU nationals living in Britain to stay here permanently.

But she refused to agree to the move unless the EU grants the same rights to 1.2million Britons living abroad.

German chancellor Angela Merkel and European Council president Donald Tusk have both refused to give such a commitment. Mrs May said that justified her position.

‘It is right that we want to give reassurance to British citizens living in the EU and to EU citizens living here in the UK,’ she said.

‘But the reaction we have seen shows why it was absolutely right for us not to simply give away the guarantee for rights of EU citizens here in the UK, because, as we have seen, that would have left UK citizens in Europe high and dry.’

Migration experts pointed to the difficulty in trying to track down EU nationals living in Britain. However the residency clash is resolved, they will need to be contacted and informed of the outcome. A decision will also need to be reached on the cut-off point for granting people residency.

Madeleine Sumption, of the Migration Observatory at Oxford University, said the number of EU nationals in the UK could be as high as 3.9 million.

Yesterday Downing Street officials conceded they now hoped to conclude a deal in the early months after Article 50 was triggered. Labour’s Brexit spokesman, Sir Keir Starmer, said Mrs May should grant EU citizens rights to stay here regardless of the position of Britons abroad.

Last night, senior Tory backbencher Steve Baker – who leads a group of Pro-Leave MPs – leapt to Mr Johnson’s defence.

He said the claims were ‘yet another political attack on a UK cabinet member’, apparently by EU diplomats.