Companies whose directors dominated pension fund trustee boards made smaller pension contributions, paid higher dividends and took bigger risks with the fund's assets, according to a London Business School (LBS) study.

Mr Myners, while declining to comment directly on the study, said: "There is a very significant deficiency in trustee competency and effectiveness across the board."

He called for more disclosure about conflicts of interest of all kinds, not just those encountered by trustees but also conflicts affecting advisers.

"Trustees, particularly of large schemes, need to manage themselves in a much more business-like manner," he said.

The LBS study found evidence that directors who were also trustees - so-called insider trustees - acted in the interests of shareholders, and not necessarily scheme members.

The pension funds of blue- chip companies typically boast six trustees, of whom a quarter on average are insiders.

As well as overseeing smaller company contributions, insiders were able to channel company funds away from the pension scheme and towards investment in the company, the study found. There was no evidence, however, that insiders were making less conservative actuarial assumptions in an attempt to reduce the official pension fund deficit.

Alex Waite, partner with Lane Clark & Peacock, said that, if necessary, insider trustees could abstain on issues where they were conflicted. Only "in a handful of cases" had he known insiders resign because of the problem.

Company directors brought financial expertise to trustee boards and help in gauging the financial covenant of the sponsoring company, he said.

New rules forcing pension funds to have at least one-third of trustees nominated by members would not come in until April 2006, it said. Eventually the aim was to lift the ratio to half.