Arron Banks, pictured with Donald Trump and Nigel Farage, says he is under threat of subpoena

The prominent “leave” campaigner and millionaire businessman Arron Banks expects to be called to Washington to give evidence before the Senate into alleged ties between the Kremlin, Brexit and Donald Trump’s presidential campaign.

The business tycoon has already been asked to supply information to the Senate judiciary committee investigating alleged Russian interference in the 2016 presidential contest.

Now he claims he has been “tipped off” by the US authorities that he will be called to give evidence to the committee under threat of subpoena, which means he could be barred from America if he fails to attend.

Earlier this year the former Ukip donor had threatened to sue Atlantic Council, a Washington-based think tank, over claims that he is a “pro-Russian actor”.

The businessman, who