Immigration extremists would be “neutralised” if the UK leaves the EU and “takes back” control of its borders, Boris Johnson has argued.

The leading Leave campaigner said those who “play politics” with immigration would be silenced if the UK was able to take charge of a “completely out of control” system.

He also repeated his calls for an amnesty on illegal immigrants who have been in the UK for more than 12 years, insisting he is “pro-immigration”.

He was speaking alongside Conservative colleagues Justice Secretary Michael Gove, work and pensions minister Priti Patel and Labour MP Kate Hoey at a Vote Leave rally in central London on Sunday.

Mr Johnson said: “I would go further, I’m not only pro-immigration, I’m pro-immigrants.

“And I am in favour of an amnesty of illegal immigrants who have been here for more than 12 years, unable to contribute to this economy, unable to pay taxes, unable to take proper part in society.

“I’ll tell you why. Because it is the humane thing to do. It is the economically rational thing to do.

“And it means taking back control of a system that is at the moment completely out of control.

“If we take back control of our immigration system with an Australian-style points based system, we’ll be dealing fairly and justly with every part of the world and we will be neutralising people in this country and across Europe who wish to play politics with immigration and who are opposed to immigrants.

“That is the way forward. To neutralise the extremists.”