SAO PAULO, BRAZIL, JUNE 19 -- Summary executions, torture and police violence are increasing in Brazil, where, despite the transition to democratic government, offenders still act with almost total impunity, according to Amnesty International.

"Police have responded to increasing social violence by taking the law into their own hands, torturing and killing ordinary criminal suspects," said the London-based human rights group. "To tolerate these abuses is to condone them," it said, accusing Brazilian authorities of failing to fulfill their constitutional obligations.

Amnesty's reports on past governments have provoked official outrage, but a Justice Ministry spokesman said the report's allegations would be investigated. He said the new administration was firmly committed to modernizing the prison system to guarantee human rights, and to reducing police violence.

Yet police abuses have multiplied since March, when the government of President Fernando Collor de Mello took office, said Tricia Feeney of Amnesty's London office. She cited a dramatic rash of killings in Rio and Sao Paulo, where in May, death squads were killing up to 20 people, often vagrants, on some nights. Death-squad suspects detained in Rio have recently been released, allowing them to intimidate trial witnesses, she said.

In northern Brazil, killings of rural labor unionists are up, while prison inmates are reported to have been beaten. Feeny said the justification was that any means were valid to counter rising crime at a time when public confidence in the police and judiciary is falling.

A recent report by Rio's police chief said at least half of the death squads were made up of off-duty policemen.

The report asserts that torture is endemic in Brazil and is one of the main "techniques" used by police for solving crimes. It said criminal suspects in one police station were beaten with a wooden bat inscribed "human rights."

In contrast, the number of policemen punished is minuscule, said Amnesty. "The fact that there are few investigations or prosecutions can only encourage police to act as if they were beyond the law," the report said.

Amnesty identifies summary killings here as a form of population control in a country where prisons are so overcrowded that it lacks prison space in which to jail more than 230,000 convicted criminals. Homicide is the main cause of death for adults in Sao Paulo.

Violence also is increasing against the 11.5 million children living in poverty, many of them in the streets. Death squads were blamed for one-third of the violent deaths of all children.