Lord Myners, the minister charged with clamping down on tax avoidance, ran two more businesses that controlled substantial offshore funds, it emerged yesterday.

The disclosures come a day after it was reported that the peer set up an offshore company in the tax haven of Bermuda of which he was part-time chairman. That company — Aspen Insurance — avoided more than £100 million a year in tax.

It emerged yesterday that the Treasury minister — who has held the post for less than six months — was also chairman of an offshore fund based in Jersey called Liberty Ermitage. He was appointed to that role in 2006. In addition Gartmore, the fund management company that Lord Myners chaired for 15 years until 2001, ran a Jersey-based offshore business.

It is the latest blow to the peer’s credibility. Earlier this month he was grilled by MPs about why he had failed to scrutinise RBS more carefully last year about the size of Sir Fred Goodwin’s pension. Sir Fred, the former chief executive of RBS, sparked public fury when it emerged that he had been awarded a discretionary 50 per cent boost to the value of his pension pot, leaving him with a retirement scheme worth £16.9 million.

George Osborne, the Shadow Chancellor, said: “Each day brings more revelations about Paul Myners’ alleged involvement in offshore tax avoidance and his failure to stop Sir Fred Goodwin’s pension. It is difficult to see how Gordon Brown can, on the one hand, claim he is cracking down on offshore tax havens, and at the same time keep as a Treasury minister someone who appears to be involved in them.”

Vince Cable, the Liberal Democrat Treasury spokesman, said: “The people charged with overseeing and policing what are effectively publicly owned banks are people who are entirely familiar with the City culture of tax avoidance and extremely large pensions. These people are not sensitive to the dangers and risks involved.”

Offshore funds allow wealthy individuals to house their money legally outside Britain, beyond the reach of the taxman.

A spokesman for Lord Myners said: “All of his past business roles are a matter of public record and he has made a full declaration of his interests. It would be impossible to find a person with senior experience in financial services who had not worked for a company with interests in many jurisdictions, including offshore centres.

“As he has said previously, all of his UK and foreign income and capital gains are taxed in the UK at the relevant rate. The experience he brings continues to be hugely valuable to the Government at a time when we are working to restore and rebuild the banking sector.”

Separately, The Times has learnt that members of the Treasury Select Committee will discuss today whether to recall the former chairman of RBS.

Members of the select committee, which is coming to the end of its inquiry into the banking crisis, will meet in private to discuss whether to take up Sir Tom McKillop on his offer to return to the Commons to give new evidence to MPs over Sir Fred’s pension, or whether to request that he send a written deposition to MPs.

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