Jan 7 (Reuters) - British advertising group M&C Saatchi (SAA.L) on Friday rejected a takeover offer from its biggest shareholder for an all-share deal, saying the proposal did not reflect the value of the business. Director Vin Murria"s investment vehicle AdvancedAdvT (ADVT.L) offered M&C investors 1.86 new shares in exchange for each M&C share they own, M&C Saatchi said in a statement. "It is not clear to the independent directors how shareholders and other stakeholders would benefit from ownership dilution and a change in board leadership of the company," M&C Saatchi said, urging shareholders not to take any action. On Thursday, M&C Saatchi revealed that Murria had told the advertising group she intended to make a bid for the company in which she currently owns 12.5% directly and 9.8% through AdvancedAdvT. read more