The Screen Actors Guild’s battle over its strike authorization has taken an especially nasty turn, thanks to a suggested boycott of eight actors who are up for SAG awards.

The proposed boycott came to light after a significant number of SAG members received a pair of anonymous emails forwarded by national board member Frances Fisher. The two emails proposed that the SAG members withhold their award votes for the eight thesps because of their public support for the opposition to the authorization vote.

Nearly 2,000 SAG members — including George Clooney and Tom Hanks — have declared that they oppose the authorization due to the nation’s current financial crisis.

In her email, Fisher said the letters were forwards and asked that her name and email be removed if the recipient chose to forward the letters. In a response issued Friday, former SAG president and current board member Richard Masur compared the anonymous email to a blacklist and called on Fisher to repudiate it.

The anonymous email singled out Josh Brolin (who was nominated for “Milk”), Kevin Spacey (“Recount”), Susan Sarandon (“Bernard & Doris”), Michael C. Hall (“Dexter”), Sally Field (“Brothers and Sisters”), Alec Baldwin (“30 Rock”), Steve Carell (“The Office”) and Tony Shalhoub (“Monk”).

“If I were a regular, ordinary, not-rich-and-famous actor, and if I wanted my union to be strong so it could fight for me … would I want to give any of these rich-and-famous UNION-UNDERMINERS my vote?” one of the anonymous emails said. “Would I want my union to give them such an honor — MY UNION’s ultimate stamp-of-approval? I would remember those names when I began to mark my ballot.”

In his response, Masur said that there has never previously been an attempt to politicize the SAG Awards over its 15-year history.

“These awards were conceived of as an opportunity for actors to be honored by their peers,” he added. “The sole criterion for the awarding of these honors has been artistic achievement. That must continue to be the case. The SAG Awards have meant a great deal to the members, the Guild and the SAG Foundation, as well as all the honorees. It would be a shame if this worthy process were to be sullied by this political manipulation.”

Masur said Fisher should send out a message to everyone to whom she sent the email with an apology and a condemnation. “That would go a long way toward repairing he perception that she meant to support and encourage this kind of outrageous blacklisting,” he added.

Fisher was not immediately available for comment. But SAG’s awards committee issued a statement condemning the anonymous email.

“The Screen Actors Guild Awards has always been and will always remain non-political,” the panel said. “It is unfortunate that a few people have chosen to attempt to politicize our annual salute to excellence in our profession. We know actors value outstanding performances and cherish their yearly opportunity to commend the good work of their peers above all else. We look forward to celebrating the achievements of our nominees on January 25th.”

The controversy comes with the guild’s emergency national board meeting set for Monday and Tuesday to determine the fate of the proposed referendum. The SAG Awards will be held on Jan. 25.

SAG leaders have insisted that the authorization will give the guild more leverage in its long-stalled film and TV contract negotiations with Hollywood’s majors. The vote had been set to be sent out Jan. 2 but after protests from SAG’s New York board and other branches, SAG prexy Alan Rosenberg delayed the start of the three-week referendum process and skedded the board meeting to address the dissent and the call from the New York board for the negotiating committee to be replaced.

Supporters of the authorization have asserted repeatedly that the new-media terms of the congloms’ final offer will lead to the eventual elimination of residuals — a contention that’s widely derided by the companies, noting that the DGA, WGA, AFTRA and IATSE have agreed to similar terms. SAG’s web site currently lists 3,800 members who support the authorization including Mel Gibson, Holly Hunter and Martin Sheen.