Anti-communist insurgents Saturday offered limited amnesty to Afghan government soldiers as Soviet troops prepared for the start of their withdrawal from Afghanistan.

Gulbadin Hekmatyar, chairman of the seven-party Afghan guerrilla alliance, said Afghan security forces who voluntarily surrender within four weeks after Soviet troops have left their districts would not be tried for war crimes."Once captured . . . they will face Islamic courts," Hekmatyar said at a news conference at the alliance's Peshawar headquarters. He did not say what punishments they would face if convicted.

The insurgents have vowed to continue their fight until the last of the Soviet troops leave Afghanistan and the Marxist government falls.

Hekmatyar said the rebels had postponed a swap of one Soviet prisoner for 25 captured guerrillas. He said his group will keep Soviet prisoners until it establishes an Islamic government in Afghanistan.