(Reuters) - CalPERS, the biggest U.S. public pension fund, said on Wednesday it plans to withhold votes for nine Wal-Mart Stores Inc (>> Wal-Mart Stores, Inc.) board members amid allegations that the retailer's top brass failed to adequately investigate widespread bribery in Mexico.

The California Public Employees' Retirement System is the latest shareholder to publicly voice concerns over the board's role after the New York Times in April reported that Wal-Mart de Mexico (>> Wal-mart de Mexico S A B de C V), which is majority-owned by Wal-Mart, used illegal payments to win market leadership in that country and that top Wal-Mart executives knew about the matter and tried to cover it up.

CalPERS said it plans to withhold votes from Chief Executive Mike Duke, former CEO Lee Scott, Chairman Robson Walton and six others.

CalPERS said it believes the nine were in positions of authority, oversight or management of the company's operations during the period when the alleged bribery took place.

The other six are James Breyer, Michele Burns, Douglas Daft, Jim Walton, Christopher Williams and Linda Wolf. Wal-Mart has 16 nominees in the June 1 election.

(Reporting by Jessica Wohl and Lisa Baertlein in Chicago; editing by John Wallace)

Stocks treated in this article : Wal-mart de Mexico S A B de C V, Wal-Mart Stores, Inc.