The United States has agreed to pay $5.7 million to a group of Texas asbestos workers in an unprecedented settlement offer that some legal experts yesterday predicted could expose the federal government countless costly claims for damages.

The offer was made secretly in September at the conclusion of a 4 1/2-year trial in Tyler, Tex., who sued the United States and several private firms on the grounds that public and private negligence resulted in their exposure on the job to a type of asbestos called amosite. Amosite has been shown to cause lung cancer in humans.

No reply has been filed to the federal offer and a U.S. district court judge in Tyler has sealed any settlement information about the case until at least Thursday. Information on the settlement was provided to The Washington Post yesterday by knowledgeable sources.

The impact of the settlement offer was spelled out last December in a memorandum on the case by attorneys for the Department of Health Education and Welfare. They warne that if the asbestos workers won, [WORD ILLEGIBLE] time a workspace proved unsafe the government had inspected should have inspected, the government would probably have to [WORD ILLEGIBLE] compensation.

According to the sources, the posed settlement involves payment about $8 million to the worker PPG Industries, which co-owner Tyler asbestos plant with the C Glass Works between 1962 and when it was shut down.

The Proposed settlement, according to the sources, also involves payment of $5.2 million by a group of British and African asbestos supplies to the plant and $1 million by the Union Asbestos and Rubber Co., which owned the plant before 1962.

The $5.7 million federal portion of the proposed settlement was arrived at as a result of threee charges by the workers:

That some asbestos used in the plant came from federal stockpiles in unmarked and unsafe burlap sacks.

That federal inspectors found high levels of asbestos in the air at the plant but failed to warn workers, telling only the plant's management under a pre-arranged secreey agreement.

That since the plant was operating under a federal contract to supply asbestos insulation to Navy vessels it fell within the provinces of the federal Walsh-Healy Act. The act requires the government to make sure that federal contractors ensure a safe workplace.

The Tyler workers sued the companies and the federal government after a rare form of lung cancer known high numbers among the plant's employees and former employees. Mesothelioma is a cancer of the lung lining that has been linked to ashestos exposure and is always fatal. Other workers said they had contracted asbestosis, a painful lung disease also connected to asbestos exposure.

Among the workers involved in the suit are several who contracted one of the lung diseases. The suit also includes the survivors of about 25 people who died of one of the disease after working at the Tyler plant's air.

Instead, according to the suit, federal health officials signed a confidentiality agreement with the Pittsburgh-Corning management to provide the results of their air samples only to the owners.

The federal health survey results were eventually published in the form of requests for tighter asbestos exposure standards but the names of the plants the federal team examined were never made public.

The Tyler workers have also claimed that the same time that the General Services Administration was shipping asbestos from federal stockpiles to Tyler in unmarked burlap bags, other federal agencies were demanding that private asbestos manufacturers label all asbestos shipments as dangerous and have them meet stringent federal protection standards.

Federal legal experts, who asked not to be named yesterday said the agreement to settle by Justice Department attorneys who handled the case could open the way for massive numbers of suits against the government by those who believe they were victims of alleged federal negligence.

"I would say there's a very strong possibility that anyone in a health-hazardous situation where the government was charged with protecting them might come forward because of this decision and make a strong case," a federal attorney close to the Tyler case said yesterday.

Justice officials who handled the Tyler case declined yesterday to comment on any possible settlement offer because the case has not yet been concluded and is under judicial seal.

"If such a settlement were to be made," said one attorney, "we do not regard what happens as having a significant impact on either pending or future asbestos-related litigation." The attorney said the Tyler case was "a hybrid" and involved an unusual combination of charges and defendants.

Another federal attorney said yesterday the proposed settlement could extend to every industry where federal investigators are obligated to inspect, even if they had not done so.

"It's a virgin territory with little to go on in the way of precedent" he said. "At this stage we just don't know how far it will carry."