In a highly unusual public inquest, witnesses have testified that Zimbabwean officials attempted to cover up the deaths of four persons killed in a confrontation with soldiers of the North Korean-trained 5th Brigade in the southern Matabeleland region last year.

A provincial magistrate last week told the hearing he was threatened with detention by a police official when he tried to pursue his investigation into the deaths of the four, one of whom was an Army lieutenant from another brigade.

The magistrate, George Romilly, also testified that as a result of his efforts, he received a circular from the chief magistrate's office specifying that "matters of this nature were not to be investigated by magistrates." He said he and other magistrates were ordered not to appear before an official commission of inquiry appointed by Prime Minister Robert Mugabe to look into charges of 5th Brigade atrocities in the region.

A local police official, Amos Ngwenya, testified that he destroyed two pages from a police docket on the deaths under orders from unnamed superiors.

The deaths of the four, which occurred Feb. 11 of last year, were among dozens of shooting incidents involving soldiers and civilians over a two-year period in Matabeleland, where the Army conducted a harsh campaign against armed dissidents opposed to the Mugabe government. Although no definitive statistics have been compiled, witnesses, aid workers and church officials in the region have alleged that hundreds of civilians died in two crackdowns in 1983 and again early this year.

The government has contended that the number of civilian deaths has been grossly exaggerated and that many died in "cross fires" between government soldiers and guerrillas. Official spokesman John Tsimba said today the government had no comment but was studying the testimony at the inquest, held by a magistrate in the southern city of Bulawayo.

Virtually all of the civilian deaths have gone without a public inquest, which Zimbabwean law permits but does not require. This case differed because one of the victims was an Army officer and because the magistrates involved, Romilly and Gordon Geddes, who is presiding over the hearing, have insisted that the matter be aired publicly.

Geddes rejected an Army request that the hearing be held in camera for security reasons and has placed on the record results of an Army board of inquiry hearing that concluded the four victims were killed by soldiers "to avoid any witnesses."

According to its account, 1st Brigade Lt. Edias Ndhlovu and three other persons were traveling in a car stopped by 5th Brigade soldiers in February 1983 near the village of Lupane during the height of the counterinsurgency operation.

Local police later issued a finding that the four had died "when caught in a cross fire in a contact between security forces and dissidents," according to magistrate Romilly. He called the finding "a fabrication" because three of the four had died from bayonet wounds, not gunshots.

In contradiction to the police finding, four soldiers involved in the incident told the Army board of inquiry that the four had been killed while trying to escape after admitting they had aided dissidents operating in the area.

Romilly, who was provincial magistrate for Lupane at the time, said he approached a 5th Brigade major to inquire about the incident and said the major told him, "as far as he was concerned, he and his men were above the law and did not have to answer to civilian authorities."

Romilly said he later received a phone call from Noah Mvere, assistant police commissioner in charge of Bulawayo, who accused him of interfering with national security matters and threatened to have him jailed for subversion.

Police inspector Ngwenya, head of the Lupane police station, testified that he did not investigate the matter because he had been told in a briefing by 5th Brigade commander Brig. Parence Shiri and assistant police commissioner Emilio Shavura "that for the purpose of the operations, I was blind and I will be told when to look up." Shavura, who also testified, strongly denied Ngwenya's statement.