The Financial Conduct Authority and Department for Work and Pensions are telling workplace pension schemes to publish annual reports on their portfolio transaction costs, picking up on a campaign launched a year ago this month by former Hermes activist David Pitt-Watson.

Pensions minister Steve Webb said: "It's important we understand all the charges that are placed directly and indirectly on pensions. There is a fear that the dark corners of the investment and pensions industry hold some nasty surprises. We have a duty to throw light on potential hidden charges."