UK regulators have given Royal Bank of Scotland and Lloyds Banking Group until March to begin dealing with a black hole that Brooks Newmark, a Tory member of the Treasury Select Committee, suggested could be as large as £30bn.

Bank officials refused to quantify the capital shortfall in evidence to the TSC yesterday, but they confirmed it was substantial, the Telegraph reports.

Michael Cohrs, a member of the Bank’s Financial Policy Committee, said it was “a big number” while Andy Haldane, the Bank’s executive director for financial stability, agreed it was “material”.

The warning came as regulators admitted that the Government had overpaid when rescuing the banks in 2008 and that the taxpayer would never make as large a profit from the bail-outs as the US, if at all.

Asked whether returns for the UK taxpayer might match the 15% made in the US, Mr Cohrs said: “I don’t think the UK taxpayer will get those returns.” Pressed on whether the taxpayer would make a profit at all, he added: “I don’t know.”