Boris Johnson and Alex Salmond have clashed over immigration, with the former London mayor warning of the issue fuelling the "rise of far-right parties" in Europe.
But the ex-Scottish First Minister accusing him of talking "nonsense" over his promises if the UK votes for 'Brexit'.
Johnson, Leave's cheerleader-in-chief, refused to put a figure on what the total should be reduced to - though hinted at the tens of thousands that is Tory policy.
However, he insisted the British people had not given consent to growth equal to the "size of the city of Newcastle".
He said: "There's a reason why across Europe you are seeing the rise of far right parties.
"It is the reason why your see immigration escalating in the whole conversation at the moment. People feel they haven't given democratic consent to what is happening. It is because we don't have control."
But Salmond hit back, accusing Johnson of promising the Brain family in northern Scotland - set to be sent back to Australia after to years in the UK - they could remain while signalling crackdown in England. He said: "It is a nonsense in this campaign. It is a total nonsense, Boris, and you know it."
Labour's Liz Kendall, backing Remain, condemned immigration being treated as if it is a "disease". Conservative employment minister Priti Patel was also arguing the case for ‘Leave’ - and warned how Labour had lost control.