More than 1,000 Peruvians have disappeared after being detained by police and the military, and hundreds of them have been reported killed since nine mountain provinces in southern Peru were placed under military administration two years ago, Amnesty International reported yesterday.

"In most cases of political killings . . . believed to have been carried out by government forces, the bodies of the victims, when found, are naked, marked by torture, and with single gunshot wounds to the head; in many cases the victims are found blindfolded and with their hands tied behind their backs," the human rights group said in its report.

"Many victims are unidentifiable; their clothing has been destroyed, features mutilated and bodies dumped far from the scene of detention, in areas where relatives are unlikely to travel."

An emergency zone, which has been extended to 13 provinces in Huancavelica, Ayacucho and Apurimac departments, was put under military command in December 1982 in an effort to curb Maoist Shining Path guerrillas.

Amnesty International said it has received reports of "scores of killings" by the guerrillas and emphasized that it condemns torture and killings by them as well.

Human rights violations on the such a large scale are unprecedented in modern Peru, Amnesty said. The victims, for the most part, have been peasants, local leaders, teachers and students.

Relatives of the missing persons report being threatened by the military when they look for their loved ones at known dumping grounds, "which are always near main roads regularly patrolled by troops or police," the organization said.

Amnesty credited the office of Peru's attorney general and the judiciary with making efforts to protect the rights of local residents and for uncovering some abuses, but it said they have been unable to halt them. Government prosecutors have protested publicly against the armed forces' obstruction of investigations, Amnesty said.

Zegarra Dongo, former Ayacucho chief prosecutor, reported last year that his office had received 1,500 formal complaints of prisoners' disappearances in 1983 and the first two months of 1984.

Peru ended 12 years of military rule with the democratic election of President Fernando Belaunde Terry in 1980.

A spokesman at the Peruvian Embassy in Washington said reports such as Amnesty International's are received by the authorities in Lima and the disappearances investigated on a case-by-case basis.

The Shining Path, founded at Ayacucho University and active in the Ayacucho area, has been responsible for several bombings in Lima and other cities and for the assassinations of officials and alleged police informants.

In some cases, discovery of mass graves has led to accusations against both the military and the guerrillas. Both sides were blamed when 50 bodies, all naked and bound, were discovered in fresh graves in the Andean town of Huanta last August.