LONDON, Jan 25 (Reuters) - Elementis shareholder Franklin Mutual Advisers has urged the board of the British chemicals firm to "initiate a sales process immediately" following news it had spurned another takeover approach, a letter obtained by Reuters shows.

In a letter sent to Elementis Chairman John O'Higgins on Thursday, senior Franklin Mutual portfolio managers Steve Raineri and Chris Meeker said they were "deeply concerned" that the Elementis board appeared not to be acting in the best interests of shareholders.

(Reporting by Sinead Cruise; editing by Jason Neely)