James G. Bellows, 55, officially resigned as editor of The Washington Star yesterday to become editor of the Los Angeles Herald-Examiner, while controversy continued over whether economy cutbacks and layoffs at the newspaper are imminent.

The Washington-Baltimore Newspaper Guild, which represents some 600 newsroom and commercial employees at the afternoon paper, warned its member that a "10 per cent reduction across the board is in the works." The Star employs about 1,400 persons, according to the Guild.

Star board chairman Joe L. Allbritton, besieged by staff members when he walked into the newsroom yesterday morning amid reports of Bellow; departure and imminent layoffs, told staff members that he could neither confirm nor deny that there would be layoffs. Such moves are "under review," he said.

Star columnist Mary McGrory met with Allbritton later in the day and assured reporters and editors that no cutbacks were planned.

Bellows, formely associate editor of the New York Herald Tribune, joined The Star in January, 1975, and is creditted with making major editorial improvements at the paper and bolstering staff morale.

Bellows reportedly has clashed several times recently with Star president James H. Smith, who recently arrived from the Sacramento (Cliff.) Bee. Bellows had been fighting proposed cutbacks at the paper, Star sources said.

They also said Bellows disagreed with Smith and Allbritton over the amount of coverage that should be given to local news. Bellows reportedly was fighting attempts to demphasize national and international coverage and to concentrate on local stories.

In the past week, Star assistant managing editor Jack Germond has hired two national reporters. Germond met with Allbritton yesterday and was assured that they will be able to keep their jobs, according to Star sources.

Allbritton released the following statement yesterday: "Jim Bellows has been an excellent editor. He has led our editorial and news staff to bring a lively and interesting paper to the city of Washington.

"The newspaper has been rejuvenated and now I understand he is returning to the city of Los Angeles to take on another challenge equal to, if not greater than, the one he took on at The Star."

Managing editor Sidney Epstein will temporarily assume director of The Star newsroom, according to Allbritton.

Editors at The Star say that Epstein will only be an interim editor. Allbritton said that he had not yet discussed the subject of a replacement for Bellows with anyone.

Although circulation figures for The Star over the past six months are not available yet, a reliable source in Star management said the figures "are down" from the last nembers published in March.

Bellows began negotiating with the Hearst Corp., owners of the Herald Examiner, six months ago when he was approached by Hearst Corp. Executive vice president Frank Bennack.

But six weeks ago Bellows broke off the talks, sources said, instead offering names of others who he felt could do the job.

Then Bellows reopened talks two weeks ago, the sources said. According to Hearst Corp. sources, Bellows was offered a half-million dollar budget increase, to use at his discretion. Bellows, who will start Jan. 1, will be paid about $100,000, according to sources.

The Hearst executives reportedly hope Bellows can increase circulation from the present 325,000 daily to "a goal of half a million." The afternoon paper's circulation was over 750,000 in the mid-1960s before it was struck did not end until last year.

Plans call for Bellows to bring in new writers, beef up entertainment coverage and import a team of investigative reporters to delve into the 200 small communities that make up the greater Los Angeles area, Hearst sources say.

Bellows has already hired at least one new editor for the Herald-Examiner. Donald Forst, one of three managing editors at Newsday, in Long Island, will join Bellows as his deputy in Los Angeles. Newsday is owned by the Herald-Examiner's competitor, the TImes-Mirror Corp., owner of The Los Angeles TImes.

Before approaching Bellows, Hearts offered the Herald-Examiner job to Clay Felker, the former editor of New York Magazine who has since taken over Esquire Magazine.