As British military investigators indicated they may have found evidence confirming allegations of a multimillion dollar scheme to sell bogus U.S. helicopter parts to overseas military fleets, informed sources indicated that their importer has suspended purchasers of the suspect parts.

The Washington Post reported to day that Federal Aviation Administration and the Bell and Sikorsky helicopter companies were investigating the charges made by a knowledgeable industry informant here.

The informant alleged to authorities that as much as $20 million to $40 million in phony parts were sent to Westland Helicopters. Ltd., in Ycovil, England in the last three years by a U.S. firm called Aviation Sales Corp. According to the allegations, the parts contained forged markings indicating they were top-quality, brand-name Bell and Sikorsky parts althouth they were not, and they were shipped with misleading certifications of airworthiness.

Helicopter industry official said that if the parts were illegally labled they would be potentially substandard.

David Walker, a spokesman for the British embassy in Washington, quoted a senior British Ministry of Defense official today as saying that parts with forged identification may have been found since the allegations about the scheme were made to U.S. and British officials last month. Walker declined to elaborate, and said no helicopters have been grounded because of the allegations.

George Galerstein, a senior attorney for the Bell Helicopter Co. in FortWorth, said today that Bell and Westland officials met two weeks ago in London to discuss the charges and begin an investigation.

"Westland and Bell are cooperating in an investigation to determine whether there are any unairworthy parts either on helicopters or in supply stock," Galerstein said that tests on the suspect parts have not been completed. But a top industry official involved in the investigation said today "I think Westland was taken," and indicated that the allegations are accurate.

According to the allegations the suspect parts ended up in the military helicopter fleets, the duties of which include NATO anti-submarine defense and the transport of heads of state.