WASHINGTON (AP) _ A federal court ordered Warner-Lambert Co. on Monday to stop manufacturing most new drug products until its plants meet government standards.

An exception was made for a handful of drugs considered medically necessary, which will continue to be produced and shipped.

Inspectors from the Food and Drug Administration found the company withheld test data and failed to ensure the quality of its products.

The company, which consented to the court decree with the FDA, said the move will cause its sales to drop $150 million this year.

The decree includes the manufacture and sale of such non-prescription products as Rolaids, said Susan Cruzan a spokeswoman for the FDA.

However, the company can ship some prescription and over-the-counter products it already has in inventory, the agency said.

''Patients must have confidence that the drugs they take are properly made,'' FDA Commissioner David Kessler said in a written statement. ''We will continue to work closely with Warner-Lambert to ensure that its products meet the appropriate standards.''

The agency said the company's failures did not pose ''a critical medical risk.''

Among the other lapses were improperly trained lab technicians, changing drug recipes without government permission, and failure to take action when drug batches failed lab quality tests, Ms. Cruzan said.

The FDA had been investigating Warner-Lambert because of recalls of 14 of the company's drugs since late 1992.

FDA inspectors found that the company was selectively filing lab reports on its products, Ms. Cruzan said. Reports that would have shown the drugs were chemically unstable were not filed with the government, she said.

The settlement in the form of an order from a U.S. District judge in New Jersey requires the company to hire independent experts who will monitor the manufacturing plants and report to the FDA on whether they are following federal rules.

It will mean ''an aggregate loss of sales revenue of approximately $150 million in 1993,'' Warner-Lambert President Lodewijk de Vink said in a statement. ''The losses will result from discontinuation of certain lower volume prescription products produced in Puerto Rico and losses associated with interruptions in product distribution.''

He said the company expects to post 1993 revenues of $5.9 billion.

The court order affects the company's plants in Morris Plains, N.J.; Lititz, Pa.; Rochester and Holland, Mich.; and Vega Baja and Fajardo, Puerto Rico.

Thirteen of the company's products for treatments of such conditions as leukemia, depression, hypertension, asthma and depression will continue to be produced and distributed because of their medical necessity, the FDA said.

The company said the court order allows continued manufacture and distribution of certain medically necessary products, such as Dilantin and Nitrostat, provided certain conditions are met. Likewise, certain investigational drugs will continue to be available.

The company also said it expects continued availability of Accupril, for the treatment of hypertension; Zarontin and Celontin for the prevention of seizures in epilepsy; Lopid for the treatment of cholesterol disorders; Nipent for the treatment of hairy cell leukemia; Loestrin 1/20 for oral contraception; the antibiotic Humatin; the anesthetic agent Ketalar; Choledyl for asthma; and Nardil for depressive disorders.

The company emphasized that there are no critical health issues associated with the products mentioned in the court order. The products in the marketplace are both safe and effective and there are no recalls of any products in connection with the decree, the company said.