Boris Johnson has reportedly said that he is in favour of freedom of movement.
The foreign secretary has told as many as four EU ambassadors that he supports the right of EU workers to move between nations, Sky News has reported.
One ambassador told Sky News: "(Boris Johnson) told us he was personally in favour of it, but he said that Britain has been more affected by free movement of people thn other EU member states."
Another said that Johnson "said it wasn't government policy" but that freedom of movement "corresponds to his own beliefs".
A third diplomat he had been "shocked" by the government's diplomacy on the matter.
However, a Foreign Office source said: “The foreign secretary said what he has said many times before - he is pro-immigration but wants 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.”
Prime Minister Theresa May has not yet outlined what Brexit means for the UK, having only said that "Brexit means Brexit". The government has said providing a running commentary on its Brexit stance might compromise the upcoming negotiations with the EU, and lead to a worse deal for Britain.
Nick Clegg, the Brexit spokesperson for the Liberal Democrats, said: "If these reports are to be believed then Boris Johnson, the figurehead of the Brexit campaign, is treating voters like fools. It now appears he never even believed in the central message of the Brexit campaign - to end freedom of movement.
"With every passing day the cracks in the government's Brexit position are widening into gaping holes. If they still cannot agree amongst themselves what Brexit means after five months, how do they expect to successfully negotiate a good deal for the British people?"