Former Jewish Care trustee Andrew Rosenfeld is to donate £1 million to the Labour Party to boost Ed Miliband's election campaign.
The sum follows a previous donation of £500,000 made by the property developer last year, and sees him overtake Harry Potter author JK Rowling to become the party's biggest donor, according to the Sunday Times.
Mr Rosenfeld has provided Labour with major financial support in the past and loaned the party £1m when Tony Blair was Prime Minister. The money was repaid in 2009 and was followed by a reported further £1m donation two years ago.
He is now the party's chairman of nations and regions and volunteers to raise support and money around the country. In the past Mr Rosenfeld has also supported the Conservatives, giving £10,000 to Ken Clarke's party leadership campaign in 2001.
The 50-year-old multi-millionaire has returned to Britain after spending five years in Switzerland. He made an estimated £100m through a property investment company, Minerva. He sold the firm in 2006 and moved his family to Geneva.
Mr Rosenfeld has rejected claims that he moved abroad to pay less tax. He said he lived in Switzerland for "lifestyle reasons" and that he had paid Swiss tax during his time in the country.