Buyout firm Blackstone and charity Wellcome Trust are reported to have launched a joint bid for more than 300 Royal Bank of Scotland branches, a source familiar with the matter revealed on Friday.

The Trust's investment, revealed to be responsible for providing £650m of funding for the charity's activities from a £14bn investment portfolio, has been taking a more concerned role in private equity consortiums in recent years.

It previously has an involvement in bank ownership having been part of the consortium that bought United, a Florida-based bank.

RBS, of which 84 percent is owned by the Government after receiving a taxpayer-funded capital feed at the time when the banking crisis is at its apex, is selling 318 of its branches so that the bailout complies with European Union state aid rules.

Blackstone and Wellcome both have a tough competition from Banco Santander, widely as the front runner, together with National Australia Bank, and Virgin Money, Sir Richard Branson's banking operation.