Government officials are waiting to hear from investigators sent to southwestern Matabeleland before concluding whether graves found there contain the bodies of six foreign tourists abducted by armed insurgents in July 1982, diplomatic sources said today.

They said Minister of State for Security Emmerson Munangagwa has told senior diplomats from the United States, Britain and Australia that forensic medicine experts were sent to the southern city of Bulawayo earlier this week to examine remains from the two graves.

The kidnaped tourists, all males, included two Americans, two Britons and two Australians. Their abduction was one of the earliest acts of political terrorism that wracked this country after Prime Minister Robert Mugabe dismissed from his Cabinet opposition leader Joshua Nkomo, his former political ally and a fellow leader of the successful liberation struggle against white-minority rule here.

Since the abductions, hundreds of blacks and several dozen white Zimbabweans have been killed in political violence between government supporters and Nkomo's followers. Nonetheless, the kidnapings have continued to hold international attention and the resolution of the case has become one measure of the Mugabe government's ability to maintain control over law and order here.

Spokesmen for the three embassies said today that they have informed the families of the victims of the new development in the case. "We have alerted the State Department, which in turn has informed the families involved that the government has a new lead in the case and a team of experts on the scene investigating," said Gibson Lanpher, deputy chief of mission at the U.S. Embassy here.

Director of Information John Tsimba said the government had no new developments to report on the case and no further comment. Other sources said officials were furious that news of the discovery had been leaked to the press before investigators could determine conclusively whether the remains in the graves were in fact those of the kidnap victims.

Diplomatic sources cautioned that the case was still far from resolved. "We've been on this for 2 1/2 years, and we've had a lot of false alarms," said one diplomat.

The possible break came early this week when an alleged dissident captured by security forces told investigators that he had been part of the gang that had abducted the tourists, sources said. The prisoner then led investigators to two grave sites, telling them one contained the body of one victim, with the other five in a second grave.

The six, who included Kevin Ellis, 23, and Brett Baldwin, 24, both of Seattle, were abducted while traveling north on the road from Bulawayo to Victoria Falls on July 23, 1982. An intensive manhunt produced no concrete leads. Some investigators concluded that the six had been murdered and buried soon after the abduction, and others suggested that some or all of them might have been marched to neighboring Botswana or Zambia.

The self-proclaimed leader of the kidnapers, Gilbert Ngwenya, was captured by security officials last year and told a Harare court that the six had been seized by a group of 17 armed men and were still alive and being held in Zambia. Both Zimbabwean and Zambian authorities said there was no evidence to support Ngwenya's claim.