By Norman Smith
Chief political correspondent, BBC Radio 4
The taxpayer owns 80% of RBS
Taxpayers may have to wait until 2015 before they start getting back the £40bn used to prop up failing banks, the BBC understands.
UK Financial Investments (UKFI) believes it may take that long before it can sell most publicly owned shares in RBS, Lloyds and Northern Rock.
The government body had been hoping to offload them sooner, but there are fears this could result in huge losses.
The Lib Dems and some senior Tories say UKFI must be more open about its plans.
Ministers have been careful not to put any timetable on a sell-off of government bank shares, as it is feared this could drive down the value of shares and cause significant losses.
It is understood that UKFI is working on the basis that recouping most of the taxpayers' money could take up to five years.
Even if this happens, it is thought the Treasury may have to retain a smaller stake in the banks for many more years.
There has been mounting pressure at Westminster for UKFI to be more open about its operations.
It is understood that the body is now prepared to report twice yearly to Parliament through the Commons Treasury select committee.
Liberal Democrat Treasury spokesman Lord Oakeshott told the BBC that UKFI was "not accountable at all".
He added: "They operate really in the dark, although they are responsible for tens of billions of British taxpayers' money.
"They are the ultimate absentee landlord. It's quite inappropriate when these banks are so central to the British economy that they've been rescued by the taxpayer that there is no proper democratic control and accountability."
UKFI, through its 80% share in RBS, is often involved in highly controversial decisions, such as when it enabled the US firm Kraft to buy out Cadbury's.
MPs complain that they cannot exert any leverage or get any answers, with ministers insisting UKFI is an arm's length body for which they are not answerable.
Independent MP Dai Davies, who has been campaigning to force UKFI to block big bank bonuses, said: "The sadness is that the government of the day, they turn around and say they are independent, they are experts in their field.
"Well, let us see that expertise. Let us talk about it. I think that barriers between us and groups like the UKFI are used as a defence by the government."
Senior Conservative MP John Redwood said: "I think the immediate change should be that a Conservative minister should immediately require that they make much more detailed information available through ministers to the House of Commons."
Fellow Conservative MP Michael Fallon, deputy chairman of the Treasury select committee, said: "I think everybody now is beginning to understand we're going to be left with this stake in the banks for several - perhaps many - years and that's why we need to get the constitutional relationship right.
"First of all it should be accountable to the Treasury committee. They've appeared before us once once or twice but we need to put that on a much more regular footing.
"Secondly, they need to publish much more detail on what their strategy is and thirdly they should have to demonstrate their independence from ministers of the day because they are protecting the long-term taxpayer interest and maybe rather different from the government's current objectives."
UKFI dismisses suggestions that it should be like the Bank of England, providing quarterly reports and regular news conferences.
But it has now promised, if asked, to report twice yearly to Parliament through the Treasury select committee.