Brexit campaign leader Nigel Farage has called out billionaire open borders campaigner George Soros and his "reliable friends" for collusion on a grand scale.

Speaking in a debate on the Paradise Papers in the European Parliament, the UKIP MEP pointed out that the financier had funded the exposé.

"I say this at a time when the use of money and the influence it may have had on the Brexit result or the Trump election has reached a level of virtual hysteria," he said.

"Just last week the Electoral Commission in the UK launched an investigation to find out whether the Leave campaign took offshore money or Russian money.

"This came about as a result of questions asked in the House of Commons by one Ben Bradshaw, somebody linked to an organisation called Open Society.

"I just wonder when we're talking about offshore money, when we're talking about political subversion, when we're talking about collusion, I wonder whether we're looking in the wrong place.

"And I say that because George Soros recently gave Open Society, his organisation, which of course campaigns for free movement of peoples and supports supranational structures like the European Union, he recently gave it 18 billion dollars.

"And his influence here, and in Brussels, is truly extraordinary."