Former Jewish Care trustee Andrew Rosenfeld has declined to comment on reports of a £1 million gift to the Labour Party.
The Sunday Times reported that the pledge would be by far the most significant private donation to Labour since Ed Miliband became leader and the biggest to the party for three years.
The London property developer, who is a vice-president of the National Society for the Prevention of Cruelty to Children, previously loaned Labour £1million under Tony Blair, which was repaid in 2009.
Five years ago, at the height of the cash-for-honours controversy, it was revealed that he was one of a number of businessmen recommended for a peerage, although he did not receive one. There was no suggestion, however, that he had asked for or been promised an honour in return for his support to Labour.