UPDATE 2-Proxy advisers oppose 3 Axcelis board directors

(Updates with Axcelis comment)

By Anupreeta Das

SAN FRANCISCO, April 18 (Reuters) - Proxy advisory firms Riskmetrics and Glass Lewis on Friday recommended that shareholders of Axcelis Technologies Inc (ACLS.O: Quote, Profile, Research, Stock Buzz) withhold votes to oppose election of three directors at an upcoming annual meeting.

Riskmetrics made its recommendation on the grounds that Axcelis, which is currently fending off a $615.6 million takeover bid from Japan's Sumitomo Heavy Industries (6302.T: Quote, Profile, Research, Stock Buzz), failed to recommend that shareholders approve a proposal to declassify the board.

Classified boards are harder to dislodge at annual shareholder meetings because directors come up for re-election at different times.

If elected, Axcelis's three board nominees would serve a three-year term each. The board currently has seven directors.

Axcelis's corporate bylaws also say that any nominee who has a greater number of votes withheld than voted in support must offer to resign.

"Axcelis urges shareholders to vote in favor of the nominees to the Axcelis board," said Robert Siegfried, a company spokesman.

Riskmetrics did not comment on Sumitomo's $6 a share bid saying it did not have enough information, but acknowledged in a note that if shareholders follow its recommendation, it may appear to be a protest against Axcelis' stand on the bid.