ISLAMABAD, Pakistan -- U.S.-backed Afghan guerrillas, profiting from a failed coup against the pro-Soviet Afghan regime, have reoccupied strategic positions near Kabul and forced the surrender of a government convoy, Western diplomatic sources said Tuesday.
The sources also confirmed the alleged coup leader, former Afghan defense minister Gen. Shah Nawaz Tanai, fled to Pakistan with his family on March 7, but said he is believed to have returned to Afghanistan. The reports contradicted Pakistan government statements that Tanai had never crossed the border.
The Afghan government alleges Tanai led the revolt on March 6 backed by Moslem fundamentalist guerrilla leader Gulbuddin Hekmatyar.
Rebel military units bombed Kabul, including the presidential palace, and fought street battles with forces loyal to President Najibullah in the most serious threat to his regime since Soviet troops withdrew one year ago.
But about 20 generals involved in the revolt fled to Pakistan on March 7 when it became clear the attempt had failed.
Official sources have said Tanai arrived aboard a military helicopter with his wife and three children near the Pakistan border city of Peshawar. The Pakistani government insisted he landed on the Afghan side of the border and returned to deeper inside Afghanistan.
Tanai 'flew to Pakistan during the afternoon of March 7, where he met with (guerrilla) leaders,' one diplomatic source said Tuesday. 'Usually reliable sources believe he is now inside Afghanistan.'
The diplomatic sources said the Pakistan-based Moslem guerrillas, who have been fighting the communist government since 1978, have taken advantage of military opportunities accorded by the coup attempt. They said large numbers of guerrillas left Pakistan to launch new operations against the regime.
One source said 'the most significant resistance gains' occurred in eastern Logar Province, where the guerrillas, known as Mujahideen, reoccupied all positions along a 15-mile stretch of highway leading south from Mohammad Agha town, 21 miles south of the capital.
The government captured the positions in heavy fighting on Jan. 6. But the sources said the guerrillas were able to retake the area because many of the forces defending it were withdrawn to Kabul to support Najibullah during the coup attempt.
They said a convoy bound for the besieged eastern city of Gardez and consisting of 80 loaded trucks and seven armored vehicles, including tanks, surrendered to the resistance in Logar on March 6 or 7.
The sources also reported heavy fighting around the eastern garrison town of Khost, where they said the guerrillas captured several outposts.
A massive resupply convoy bound for Khost left Kabul in January and reached Gardez, about 40 miles northeast ofthe town, last month. The sources said Khost, which is surrounded by guerrilla-held territory and has been supplied only by air for the past two years, could fall this summer unless it receives new supplies of heavy weapons soon.
The resistance holds about 90 percent of Afghanistan's territory. But it has failed to capture any major urban centers despite the completion of the Soviet withdrawal in February 1989.
The guerrillas are desperately seeking a military victory to boost their contention they are still capable of defeating the Kabul government on the battlefield.
Najibullah came to power in 1986, seven years after the Soviets invaded in December 1979 to support the first of a series of Marxist rulers against anti-communist Moslem rebels.