ALGIERS, Algeria (AP) _ Gunmen shot to death two Spanish nuns as they left a chapel in downtown Algiers on Sunday, officials said.

There was no immediate claim of responsibility for the attack.

But the Armed Islamic Group, which has targeted foreigners in its campaign to topple the military-backed government, took responsibility for the May slaying of a French nun and French priest.

The group, the most radical Islamic faction, said at the time that those killings were part of a ''campaign of purification of Jews, Christians and unbelievers from the land of Islam.''

More than 10,000 people have been killed in Algeria's escalating violence, which began after the army canceled January 1992 parliamentary elections to thwart an expected victory by Muslim fundamentalists.

The armed men fled after Sunday's attack in the Notre Dame d'Afrique neighborhood, which is near an area that is a Muslim fundamentalist stronghold.

Sister Ester Paniagua Alonso, reportedly 63, was killed instantly.

Her companion, Sister Caridad Maria Alvarez Martine, died at the military hospital of Ain Nadja, security forces said. Medical sources said the 61-year- old sister had been in a deep coma with gunshot wounds to the head.

The nuns, of the Augustine order, were longtime residents of Algiers carrying out humanitarian work, according to Spanish diplomatic sources. They were shot as they were leaving the chapel with about a dozen other people, church officials said.

All the sources spoke on condition of anonymity.

Spanish Foreign Minister Javier Solana condemned what he called an ''undescribably violent act.''

The deaths raised to 68 the number of foreigners killed in this North African nation since September 1993, when Islamic extremists extended their campaign to topple the government by trying to scare off foreign investment.

The Armed Islamic Group claimed responsibility for the slaying on Tuesday of two technicians, French and Italian, at an oil drilling site in eastern Algeria, the French news agency Agence France-Presse reported from Paris.

Security forces, meanwhile, kept up their drive on extremists, killing 17 in various operations around the country over the past few days, they said Sunday. On Saturday, security forces said they killed 47 armed Islamic extremists over a four-day period last week.

A state prosecutor and the director of a university program were killed in separate attacks blamed on Islamic extremists, security forces and newspapers reported Sunday.

The prosecutor of Tighzirt, east of Algiers, was killed Saturday in a knife attack hours after being kidnapped, security sources said. Mohamed Arezki Chaib was the latest of some 20 prosecutors killed.

Algiers newspapers reported that Tahar Halis, 51, director of the Islamic Institute of Batna, in eastern Algeria, was slain after finishing Friday prayers at the local mosque.

Halis was a political commissioner for the National Liberation Front, the party that ruled Algeria for nearly three decades and was losing to the Islamic Salvation Front when the parliamentary voting was halted.

Halis was the fourth director of a university program killed since last May.

There were no claims of responsibility for the killings but they were attributed to Islamic extremists.