Privatising RBS could take up to 10 years, departing chief executive Stephen Hester has said.

In a weekend interview Mr Hester said the sell-off might take "four or five goes, over 10 years" if the government wanted to recoup its £45 billion investment.

He also confirmed that he did not "initiate the specifics of the discussion" about his departure, and he opposed the idea of splitting the bank into good and bad parts.

Alistair Darling, the ex-chancellor who agreed Mr Hester's appointment in 2009, said it appeared that his departure had "not been a decision by the RBS board alone as there is none of the succession planning you would expect when the CEO of a very large bank leaves".

He added: "As we have seen from the share price reaction, political meddling has had the effect of removing value from RBS rather than adding to it." RBS shares closed at 316p on Friday, down 5.4% on the week."

Chancellor George Osborne will give further details of the privatisation process for RBS and Lloyds in his Mansion House speech on Wednesday.

He has come under pressure, according to a report yesterday, from senior executives at Lloyds and at UK Financial Investments, the manager of the state's 39% holding in the bank, to limit the first tranche of shares in Lloyds to institutions, using an 'accelerated bookbuild' process, and not target retail investors in a 'tell Sid' exercise.