Indonesian forces have systematically tortured and killed in the former Portuguese colony of East Timor since they forcibly annexed the island territory in 1975, Amnesty International said in a report released here yesterday.

The report by the London-based international human rights organization details allegations of hundreds of killings of civilians during and shortly after the territory was forcibly annexed; the "disappearance" of prisoners suspected of links to the guerrilla insurgency; the torture and ill-treatment of persons taken into the custody of Indonesian forces, and the imprisonment without charge or trial of persons suspected of opposing the Indonesian occupation.

The 87-page report said there was evidence of beatings, electric shocks, sometimes on the genitals, burning with lighted cigarettes, and sexual abuse, including the rape of women prisoners.

Amnesty also said there were a number of reports, "including some of which appear to be well-founded," of executions by left-wing guerrillas fighting for the independence of East Timor. Their targets were described as those alleged to have collaborated with Indonesian forces.

The report covers the period from December 1975 through 1984 and, according to Amnesty researchers, is the first extensive report on human rights abuses on the island territory.

The Indonesian government has rejected similar previous allegations by Amnesty and other groups.

In 1975, Indonesia faced the emergence of a leftist government on the eastern half of the shared island after the guerrillas of the Revolutionary Front for an Independent East Timor, or Fretilin in its Portugese abbreviation, declared a republic after a three-month civil war. Jakarta soon invaded and later annexed the territory.

Because access to East Timor is limited by Indonesian forces, the organization has not been able to visit the predominantly Roman Catholic territory.

The information in the report is described as based on material from the guerrillas, confidential material, including copies of interrogation reports by Indonesian authorities, and interviews with former prisoners and refugees now living in Portugal and Australia, according to Amnesty officials.

According to Amnesty, Indonesian military personnel serving in the eastern military district of the territory were issued a set of military manuals by the then commander for East Timor in 1982.

One of these manuals, a copy of which was obtained by Amnesty, "contains guidelines which appear to permit the use in certain circumstances of physical and mental torture during interrogation and include advice on how to prevent its exposure," the report said.