The tycoon has now hit back at what he described as “toxic personal criticism” against him, and has denied accusations that he was “undermining democracy”.Writing in the Mail on Sunday, he told how the organisation had his “wholehearted support”, and insisted he had never made a secret of his opposition to Brexit.He said: “The fact that conditions are unsatisfactory does not mean that they can’t get worse. That is what has happened in Britain. “Before the referendum Britain was doing better economically than the rest of Europe. But this has now been reversed, with Continental economies powering ahead while Britain lags behind.”Hungarian-born Mr Soros, one of the world’s richest men who made a billion dollars betting against sterling on Black Wednesday in 1992, said Britain would “lose much of its global influence” outside of Europe. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings. 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. He added: “To make matters worse, the divorce process will preoccupy both Britain and Europe for years ahead, when they should be uniting to resist external enemies like Putin’s Russia and resolve the internal contradictions that made some people regard the EU as their enemy.”He also claimed Brexit had turned young against old, saying young people had become disillusioned with democracy after older votes “overruled” them in the referendum.Declaring to be a “proud supporter” of Best for Britain, he warned that the effect of the uncertainty created by Brexit would become “painfully obvious” in the next six months as negotiations entered the “most contentious phase”.