Moslem guerrillas fighting to topple the leadership of Afghanistan slaughtered more than 200 government soldiers who had agreed to surrender, diplomatic and guerrilla sources said Saturday.

The killings occurred last month during battles for two provincial capitals in southern Afghanistan, the sources said on condition of anonymity.Moderate guerrillas blamed Moslem fundamentalists for the massacres. Moderate groups have pulled out of the fighting, aimed at pressuring the Kabul government to negotiate an end to the 12-year-old war, the sources said.

"Everyone is denying responsibility," one diplomatic source said.

Guerrillas gunned down at least 95 Afghan soldiers who had surrendered and paved the way for the Oct. 4 fall of Tarin Kot, the capital of Uruzgan Province, sources said.

About two weeks later, they said, about 125 soldiers were slain by guerrillas negotiating the surrender of Qalat, capital of neighboring Zabul province. The guerrillas had promised the soldiers safe passage if they defected, they said.

Another 100 soldiers were holed up in a heavily armed fort overlooking the deserted city until 400 troops were flown in by the Soviet-backed Kabul government, along with food and other supplies, they said.

The reinforcements allowed the government to hold Qalat, which sources said was on the verge of falling to the U.S.-financed guerrillas.

Qalat is strategically important to the Kabul government because of a highway that links eight provincial capitals. It is the major route for resupply convoys.

Shortly before the Soviet Union ended nine years of direct involvement in Afghanistan and withdrew its soldiers in February 1989, many expected that huge defections among government troops would bring down the Kabul government within months. But their predictions proved wrong, largely because of highly publicized massacres of soldiers who surrendered to the mujahedeen.