Litton Industries, a leading defense contractor labelled by the AFL-CIO last year as the nation's worst violator of labor laws, yesterday announced an agreement with union representatives aimed at ending a long-running labor dispute that included strikes, boycotts and numerous lengthy legal actions.

The California-based conglomerate, which employs 77,000 workers in more than 30 states, said in a joint statement with the AFL-CIO that a novel labor-management committee had helped resolve two of three labor disputes at plants in South Dakota and Connecticut and would continue meeting to improve relations elsewhere.

"The language in this agreement leaves a lot of loopholes, but there is a commitment to sit down and work out disputes, which is a major reversal on Litton's part," said a spokesman for the AFL-CIO's Industrial Union Department.

Litton spokesman Robert Knapp said the company has improved labor relations in recent years, noting that 24 of its 26 contract negotiations with nine unions ended without strikes in the last round of bargaining. "We don't wish to discuss the past," he said referring to previous AFL-CIO statements.

The AFL-CIO last year pushed a Litton boycott and attempted to have the company barred from federal contracts, citing more than 20 cases in which Litton was found guilty of unfair labor practices by the National Labor Relations Board. Those cases involved firing or threatening workers attempting to organize unions and refusing to bargain in good faith once unions won elections to represent employes.

But the AFL-CIO suspended the boycott activities last year when Litton's chief executive, Fred W. O'Green, suggested setting up a five-member union-company committee to resolve disputes. The committee is chaired by a neutral party, Paul Kayser, a veteran labor relations expert.

The report said that some of Litton's divisions "may have, in exercising their preference for union-free operations, committed excesses" in opposing unions. While Litton makes no official recognition of that conclusion, the joint report said the company is committed to good-faith bargaining and would allow the five-member to operate for at least another year.