Vince Cable has cooled expectations over Royal Bank of Scotland's return to private ownership by saying it may be in public hands for another five years.

The Business Secretary said he believed there was little prospect of any sale of the Government's 81% stake taking place before the next election in 2015 and that it is probable the state will have a stake for the majority of the next parliament as well.

His comments conflict with remarks by David Cameron, who has said the stake should be sold as soon as possible, while RBS's chairman Sir Philip Hampton thinks the process could begin next year.

Mr Cable said: "I don't think it would be sensible for the Government to set a rigid timetable, but given where we start from I think it is pretty unrealistic to think of RBS going back into private ownership this Parliament or probably within five years."

The prospect of a lengthy spell in public ownership will increase the pressure on the Edinburgh-based bank to be broken up.

Investment bank Rothschild has been tasked with reviewing whether the 81% state-owned lender should be split into a "good" and "bad" bank.

Mr Cable added: "I think there is a very strong argument for saying that the bank got too big and indeed that was the source of its undoing."

A longer spell with the Government's stake still in place will increase pressure on the bank to extend more credit to the economy.

Mr Cable said: "We do need to have strong UK banks, particularly supporting our business community."