The investor, one of the world's largest with $2.8 trillion in assets under management, said it plans to begin screening European firms in the STOXX 600 <.STOXX> and FTSE 350 <.FTLC> that it invests in and engaging with them over diversity.

The move by State Street GA, which said it planned to expand the effort in the future, comes as International Women's Day ratchets up pressure on companies across the world to do more to ensure fair treatment of women on issues including pay.

"Often when we engage with companies on the issue of board diversity we hear that the biggest challenge is a lack of suitable female candidates," said Rakhi Kumar, head of ESG Investments and Asset Stewardship for State Street GA.

"Our efforts can't stop at the board level if we truly want companies to adopt policies and practices that will help strengthen gender diversity throughout their organizations, and ultimately contribute to a greater pool of female directors qualified to serve on a board."

Over the last year, pressure from State Street GA resulted in 152 listed companies, that had previously had no women on their board, move to having at least one, it said. Although 600 other firms it had targeted had yet to act.

(Reporting by Simon Jessop; Editing by Elaine Hardcastle)