A top shareholder in Adecco, the world's largest temporary staffing group, has demanded that the board "back or sack" chief executive Jerome Caille as speculation mounts the group is preparing to make a more detailed public statement about its financial worries.

Ralf Rybarczyk, senior portfolio manager at DWS in Frankfurt, said the senior management in Adecco - led by chairman John Bowmer - should pledge their support for Caille or replace him with Bowmer until a long-term chief can be found.