Vote Leave has been accused by former chancellor Ken Clarke of "Donald Trump type nonsense".
The Tory grandee and ardent pro-Remain advocate said that the leave camp was guilty of trying to scare voters on immigration.
Speaking on BBC One in the East Midlands in an EU debate special, the Conservative MP said EU migrants had helped fill jobs in the UK, while Brexit wouldn't help ameliorate the movement of people from "Syria or Afghanistan".
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"We have to take some of those people. I think we're under a moral obligation to take some of them ... but that's up to the British government. You leave the EU and it makes no difference," Clarke said.
"The Leave people have no policy at all - they are just frightening you that there are lots of rapists and murderers and child molesters coming in unless we seal our borders. This is Donald Trump type nonsense."
Last month Clarke hit out at the former Mayor of London and Brexit supporter, Boris Johnson, calling him a "nicer version of Donald Trump" and accusing him of turning the Leave campaign into a leadership bid.
However, during the debate Leicestershire MP Andrew Bridgen said wages in the UK were a huge draw for Eastern European migrants, stating that if the UK voted for Brexit wages for the lowest paid would increase.
Meanwhile, on the BBC South East debate former Conservative leader Michael Howard said: "There are people who think the current level [of immigration] is fine, and there are other people who think it's too high.
"But that's an argument that we ought to be able to have in this country, that's an argument that we ought to be able to decide in this country, and we can't decide it in this country as long as we remain members of the EU."