The chairman, Roberto Quarta, said at the beginning of the group's annual meeting that the process the board followed in response to the allegation of personal misconduct against Sorrell was robust from a governance and legal perspective.

He said share awards due in future to Sorrell pre-dated the current board's involvement in his working terms and that he accepted that some investors found the situation unsatisfactory.

"I know that questions remain, but there is simply nothing further we can legally disclose," Quarta said.

Sorrell has denied wrongdoing.

(Reporting by Sarah Young; Editing by Keith Weir)