Billionaire investor George Soros has defended his decision to hand £400,000 to a campaign arguing against Brexit - and says he considers leaving the EU a "tragic mistake".

Mr Soros came under fire last week after the Telegraph revealed he was backing the Remain-supporting campaign group Best for Britain.

The investor is one of three senior figures linked to the group who plan to launch a nationwide advertising campaign this month, which they hope will lead to a second referendum to keep Britain in the EU.

The campaign is trying to recruit major Tory donors in an attempt to undermine Theresa May.

It also plans to target MPs and convince them to vote against the final Brexit deal to trigger another referendum or general election, according to a strategy document leaked from a meeting of the group.