Two policemen, one white and one black, were killed today in separate incidents on the outskirts of a sprawling black squatters' camp here and police also came under fire from blacks in the area.

The victims were among six persons reported killed in a day of extensive violence in South Africa's black townships, now in their 19th month of civil unrest. More than 1,300 people have died in the violence, 32 of them policemen.

Police also reported killing an alleged black insurgent who they said was suspected of planting a bomb in a church east of Johannesburg last week. They said he was killed yesterday when he attacked police with a Soviet-made hand grenade.

The first policeman to die was a white constable whose body was found after daybreak burning in a pile of rubbish on a main road bordering Crossroads, the country's most notorious and densely populated squatter settlement.

Police said the constable and two other officers had been suspended from duty following allegations that they had been involved in marijuana smuggling. It is not known why he was in Crossroads.

A witness told reporters that the man had been killed in a shack in the camp during the night, then dragged outside and set on fire. Other witnesses said his body was found with a long black wire wrapped around his neck and garbage, plastic bags and bricks dumped on the corpse. Police said he had been shot but the witnesses said it was unclear how the man died.

The burning resembled the practice of black militants to use "necklaces" of gasoline-soaked tires to kill suspected collaborators with the apartheid system. It was the first time a white has been burned in such a fashion in the unrest, during which four white policemen have been killed.

After the killing, witnesses said residents gathered to stone the corpse and set alight several vehicles. Police lookouts stationed on the roofs of shacks at the scene had to duck at one point when a series of shots were fired at them.

At around noon a second officer, a black constable, was killed when he was shot in the head after he climbed out of a police vehicle. A volley of shots was heard by witnesses, and a police spokesman later said the constable was killed by a "heavy caliber rifle." No arrests were reported in either incident.

The deaths fueled speculation that militants connected with the outlawed African National Congress have stashed arms somewhere in Cape Town's black townships. Seven suspected guerrillas were killed here earlier this month and police said then they had confiscated a large array of automatic weapons.

The congress, the main black resistance group fighting white-minority rule, has publicly targeted the police for attack as "enemy personnel" enforcing apartheid.

Crossroads erupted in new violence last week when nine blacks were killed by other blacks in a power struggle between a local leader and elements loyal to the opposition United Democartic Front. A witness named Nkosana Mdini was quoted by the South African Press Association today as claiming that police had escorted him and other armed black vigilantes into Crossroads on the night that seven vigilantes, known as "the Fathers," died.

Mdini said police disappeared when shooting broke out. He was captured by UDF supporters, known as "the Comrades" and remains in their custody. A police spokesman said police would investigate Mdini's allegations if he made a complaint.

The suspected ANC insurgent killed yesterday reportedly was betrayed by fellow blacks in the Katlehong township, a police statement said. It said several weapons, including AK automatic rifles and ammunition, were found at the house where the man was killed.

Three other blacks were killed in ritual burnings reported by police today.

Two, an unidentified man and woman, were doused with gasoline and set alight at Sondagsfontein in the northern Transvaal. Another man was killed in the same fashion in Soweto, South Africa's largest black urban center