On Tuesday Tesco announced two more non-executive directors were leaving the group.Ken Hanna and Stuart Chambers, who have been in the supermarket chain for six and five years respectively, said they will retire as directors after the company's annual meeting in June.Byron Grote, another non-executive director, was to replace Ken Hanna in his role as chairman of the audit committee. Hanna is also the chairman of Inchcape and Aggreko and Chambers is the chairman of Rexam.Chairman John Allan said: "On behalf of the board, I would like to thank Ken and Stuart for their loyal and valuable contributions to Tesco, and we wish them well for the future."Five other directors have resigned this year following the Serious Fraud Office's investigation over the stricken retail giant's accounting practices.