Five more blacks have been killed in clashes with South African security forces, police reported today, and 127 more persons have been arrested in the government's crackdown on black activists.

The official death toll has now risen to 16 since the white-minority government declared a state of emergency in 36 South African cities and towns five days ago. The number of arrests stands at 792 under the declaration, which gives the police and Army sweeping powers of arrest and seizure of property.

The five deaths disclosed today by police is the highest number reported in any one day since the emergency began, although four of the deaths actually took place yesterday. The four persons were shot dead and 16 others wounded yesterday afternoon in a confrontation between security forces and a crowd in the black township of Daveyton, east of Johannesburg, according to the police report today.

An official spokesman said riot police and soldiers opened fire with rifles and shotguns on a mob stoning an Army patrol in the town. One soldier was reported injured in the clash.

One of those killed was a 16-year-old girl whose grandmother told The Johannesburg Star newspaper that her granddaughter and several other residents had been forced to accompany mourners to a funeral in the town.

Soldiers in the East Cape region shot and killed a 16-year-old black youth today in another incident in which police said blacks had stoned an Army vehicle. The police spokesman refused to name the township where the killing occurred or to identity the victim.

Police have cut back sharply on the amount of information they are releasing on such incidents as part of a campaign to play down unrest. "That's the instruction from headquarters," the spokesman replied when asked why more specific information was not available.

A police vehicle was fired on last night and a policeman was wounded when a hidden gunman opened fire with an automatic rifle in a township near Port Elizabeth. Police also reported about a dozen other incidents of unrest in various unidentified townships today and last night.

The reports of new deaths seemed to contradict police claims in recent days that unrest in the townships is winding down following the emergency declaration. At least one person has been killed daily since the proclamation, adding to the estimated toll of 450 persons who have died during the past 10 months in political violence.

Following the new police report of arrests today, a spokesman for the Detainees' Parents Support Committee, an opposition civil rights monitoring group, said he believes police are withholding the names of at least 100 persons who have been detained.

The spokesman, who requested anonymity, said more than 100 persons had been rounded up in townships southwest of Johannesburg early this week whose names had yet to appear on the official list of detainees. "Obviously there are a very large number not on the list," he said.

The police spokesman said tonight that he had no comment on the allegation.

Meanwhile, the white commissioner of police for the city of Soweto, South Africa's largest black urban center, today announced that he is banning all gatherings this weekend to celebrate the 67th birthday of black resistance leader Nelson Mandela.

Mandela, leader of the outlawed African National Congress, has served 22 years in prison on a life sentence for plotting the overthrow of the government. Many black organizations here have demanded his release as one condition for talks with the government over South Africa's political future.