TOKYO, March 5 (Reuters) - Singapore-based hedge fund 3D Investment Partners has proposed that Japan's Fuji Soft appoint an outside auditor to ensure the software developer fairly reviews multiple takeover proposals it has received from global private equity firms.

The move by 3D, Fuji Soft's top investor with a stake of some 21%, marks a change of tactics by the fund, which previously had two independent director nominees appointed to the Fuji Soft board.

Appointing an outside auditor would help Fuji Soft better evaluate takeover proposals the $2.6 billion company has received, its biggest shareholder said, as it steps up pressure on the firm to beef up the process.

A statutory auditor has a lot of powers that a director doesn't have, to check the legality and fairness of decision making, Stephen Givens, a U.S. corporate lawyer and auditor nominee backed by 3D, told Reuters in an interview.

The Yokohama-based company has launched a special committee of independent board directors to review the private equity proposals, compare them with its own business strategy and determine which would most enhance its value.

The private equity proposals were in response to requests from 3D and not something the company requested.

Fuji Soft said that it is sincerely considering the proposals and its process is in line with legal requirements and government guidelines.

Influential proxy advisor Institutional Shareholder Services (ISS) recommended in favour of the company for the annual shareholders meeting on March 15.

"It remains unclear what added value (other than giving the dissident peace of mind) the appointment of an additional outside auditor will have," ISS said, adding that the evaluation of the proposals is in the realm of responsibility of the special committee. (Reporting by Makiko Yamazaki; Editing by Michael Perry)