Opposition MPs in the UK have asked for an independent review into the use of tax havens by the banks which have recently received state funding, according to a report by The Sunday Times.

The report said that Lloyds has more than 125 offshore companies while Royal Bank of Scotland has 238, including 66 in the Cayman Islands and 30 in Jersey. It also owns Coutts & Co, which provides offshore services for high net worth clients.

Liberal Democrat Treasury spokesman Lord Oakeshott asked ministers to disclose how much the banks’ offshore subsidiaries were costing taxpayers and said he would be tabling parliamentary questions.

“The government should not put a penny more into these banks before they stop biting the hand that feeds them. Ministers need to face up to this issue now,” he is quoted as saying.

George Osborne, shadow chancellor, told The Sunday Times: “While Gordon Brown claims he will deal with offshore tax avoidance, he is increasing the government’s stake in banks that, like RBS, have offshore subsidiaries. It is another example of this government’s lack of a coherent strategy – and something will have to give soon.”

A spokesman for RBS said: “RBS complies fully with the taxation laws in all UK and offshore jurisdictions. Any changes to taxation laws in these jurisdictions are matters for regulators and governments.”

The calls for the offshore interests of UK banks to be reviewed coincides with increasing industry concern about the status of Coutts within a banking group that has significant state support. Some commentators point out that some clients may question whether wealth planning and tax structuring will be as extensively pursued as when the group was fully independent.

Meanwhile, the UK is losing at least £4 billion a year through wealthy residents holding their money in offshore tax havens, TUC research has claimed.

Jersey, followed by Switzerland, the Isle of Man and Guernsey is the most popular offshore destination, according to the TUC.

Analysing figures from a recent parliamentary answer, the TUC said during the past three years £319 million of tax was lost on a total income from offshore accounts of £1.1 billion.

But the group said the figures were a "serious under estimate" of the total tax lost to the UK through tax havens and it suggested that more than five times more money was held in offshore accounts by companies or trusts set up for wealthy clients which are not governed by the EU Savings Tax Directive.

The TUC said that around a fifth of assets held off-shore are in cash, so overall, the total amount of tax lost to the UK last year through holding assets offshore was at least £4 billion.

Lloyds Banking Group said: “We treat very seriously our obligations to comply with all tax legislation. In 2008, HM Revenue & Customs acknowledged the high quality of our tax submissions and our levels of disclosure. As two of the very largest corporate taxpayers in the UK, Lloyds TSB and HBOS always sought to have good relationships with the UK tax authorities. The board of Lloyds Banking Group intends to maintain this.”

It is thought the banks would resist any attempt from government to interfere with their commercial ability to use legal offshore tax havens in the normal course of business.

In the US the Government Accountability Office said more than eight out of ten big American firms had subsidiaries in tax havens.

A Treasury spokesman said the banks were run on an arm’s length commercial basis, but the government would continue to take tax evasion and avoidance seriously and would act to prevent it regardless of who owned the company.