A campaign to persuade more trade unionists to become pension fund trustees, to give them greater influence over company decisions, has been launched by Britain's biggest public sector union.

Dave Prentis, general secretary of Unison, said: "Concerns over corporate behaviour and asset stripping by private equity groups are strong arguments for greater shareholder scrutiny and empowerment. There is also strong evidence to suggest that the more representative fund boards are, the better they perform."