Says Killings by El Salvador Military Death Squads Escalate Embargoed For Release 8:01 p.m. EDT - Time Set By Source

LONDON (AP) _ El Salvador's security forces have killed hundreds of suspected government opponents in an escalation of clandestine ''death squad'' activity in the past two years, Amnesty International charged Wednesday.

The international human rights organization said the revitalization of death squads, often made up of regular troops and police, has coincided with the armed forces' open opposition to President Jose Napoleon Duarte's policies.

Military authorities abducted and summarily executed tens of thousands of suspected leftists in the late 1970s and early 1980s, but the killings dropped off sharply after Duarte's U.S.-backed civilian administration came to power in 1984, it said.

The government says the killings are the work of extremists who act independently and cannot be apprehended, but Amnesty International's report said ''evidence gathered over many years from a wide range of sources points to security force responsibility.''

The death squads customarily wear plain clothes, use unmarked trucks or vans with tinted windows, and often dump mutilated victims on the roadside ''as a means of terrifying the population,'' it said.

Some victims are shot from passing cars in daylight in front of witnesses, while others are seized from their homes or in the street and ''never heard of again'' or turn up in notorious ''body dumps,'' the report said.

A lava bed 12 miles north of El Salvador called El Playon, where skeletons of bodies devoured by birds of prey were common in the early 1980s, fell into disuse until an unidentified body was found there in January, it said.

Bodies also are again being dumped at a site known as the Devil's Doorway at Panchimalco, 12 miles southeast of the capital, it said.

The killings which authorities attribute to the death squads ''are routinely carried out by regular units of the armed forces which include the military and the security services, and by special intelligence units that incorporate civilian gunmen under their supervision and control,'' the report said.

In 1987, an average of 12 bodies a month ''showing death squad-style mutilations'' were found dumped along roadsides, the report said.

It said Tutela Legal, a Roman Catholic human rights group in San Salvador, estimates that as many death squad-style disappearances and killings occurred in the first quarter of this year as in the whole of 1987.

Amnesty International gave no estimate of the number of death-squad killings in the last six months.

Since early 1987, victims have included trade unionists, human rights workers, returned refugees and members of the judiciary attempting to establish responsibility for human rights violations, it said.

Abductions and attacks have often occurred near police or military installations ''or under the gaze of uniformed security personnel who made no effort to intervene,'' the report said.

The squads intimidate opponents by publishing ''death lists'' in newspaper advertisements and delivering coffins to the homes of intended victims, the report said.

Dumped bodies frequently are found decapitated, dismembered, strangled or showing marks of rape or torture, such as burns and machete wounds, it said.

Other deliberate killings have been falsely ascribed by armed forces' spokesmen to clashes with opposition forces, the report said.

Amnesty International said renewed death-squad killings ''have occurred as the armed forces high command has expressed open opposition'' to Duarte's policies, including his negotiations with leftist guerrillas.

The assassination a year ago of Herbert Anaya Sanabria, president of the Salvadoran Human Rights Commission, ''was widely interpreted as an attempt to hamper these negotiations,'' the report said.

It said reports this summer that Duarte is terminally ill with cancer have been ''another factor affording the armed forces even greater control over counter-insurgency policies.''

A 9-year-old civil war has killed an estimated 65,000 people, most of them civilians.

The resurgence of death squads also has coincided with the release of most of the country's more than 400 political prisoners in a 1987 amnesty linked with a regional peace agreement, the report said.