The heaviest Soviet-supported air and ground artillery bombardments of Afghan guerrilla positions in the area north of Kabul since the war began in 1979 has staggered resistance forces and sent thousands of refugees fleeing toward the capital for sanctuary, Afghan exiles here and western diplomatic sources in Kabul said today.

For the first time since Soviet troops intervened in Afghanistan 3 1/2 years ago, travelers from the strategic Shomali region that runs north from Kabul toward the Soviet border have carried reports of widespread "desperation" among the Afghan rebels, according to western diplomats based in Kabul.

Emboldened by the successes of the summer offensive, Soviet-backed Afghan Army forces have issued a series of ultimatums to prominent resistance leaders to surrender or face another major bombardment.

Reports from a western diplomatic mission in Kabul described the Shomali air raids as the worst since the war began in December 1979, and an Afghan exile source here called the attacks and the subsequent flood of refugees to the capital "unprecedented."

The attacks contrasted sharply with the continued absence of clashes in the normally volatile Panjshir Valley, where guerrillas and the forces of Afghan leader Babrak Karmal have disengaged in what has been reported as a tacit cease-fire agreement.

According to western diplomatic reports from Afghanistan, Soviet helicopter gunships and fighter-bombers last week pounded Charikar, capital of Parwan Province, and attacked a number of villages in the nearby Khayr-Khanah Pass, forcing thousands of refugees to flee to Kabul.

Tanks and artillery batteries stretched for 30 miles along the highway connecting Kabul and Charikar also pounded the Shomali region, after which Soviet-supported Afghan troops in armored vehicles entered the Shakar-Dara and Guldara valleys to search for Afghan rebels, diplomatic sources said.

Residents of the villages were warned against supporting the rebels, and in one village, more than 20 residents who complained about the bombardment were summarily executed, according to the reports from Kabul.

Numerous houses in Guldara were said to have been looted and destroyed by the ground forces.

The western diplomats said the resistance forces were "reeling" from the intensity of the Soviet and Afghan Army summer offensive in the Shomali area, and had become dispirited by the flight of thousands of local residents upon whom they rely for shelter and logistical support.

A guerrilla leader with the Jamiat-e-Islami organization in the town of Fazar, 10 miles from Charikar, was reported to have been given until last Saturday to surrender or face another bombardment.

The western diplomatic sources said in their delayed reports that the rebel leader rejected the ultimatum but was at a loss about how to meet another sustained bombardment.

"For the first time, we detect a note of desperation in the accounts given by travelers from Shomali," a western diplomatic analyst said yesterday.

An Afghan exile leader here said, "The situation in Shomali is taking on very ominous proportions. Each report we get is worse than the one before. They are getting very heavy bombardment."

Rebel units were reported to have fared better in Paktia Province, in southeast Afghanistan, where a large Soviet and Afghan Army force dispatched to open the road between Gardez and Khowst, the two major towns of the province, was stymied in the face of stiff resistance.

According to diplomatic reports, Khowst has been inaccessible to military convoys, and the 25th Afghan Army division there is being supplied entirely by air.

Most of Paktia Province is controlled by the moderate National Movement headed by rebel leader Sayed Ahmed Gailani.

Meanwhile, two weeks of intensive bombing of the city of Herat, in Soviets Hit Rebels in Afghanistan Raids Reportedly Stagger Insurgents, Spur Refugee Tide By William Claiborne Washington Post Foreign Service

NEW DELHI, May 10--The heaviest Soviet-supported air and ground artillery bombardments of Afghan guerrilla positions in the area north of Kabul since the war began in 1979 has staggered resistance forces and sent thousands of refugees fleeing toward the capital for sanctuary, Afghan exiles here and western diplomatic sources in Kabul said today.

For the first time since Soviet troops intervened in Afghanistan 3 1/2 years ago, travelers from the strategic Shomali region that runs north from Kabul toward the Soviet border have carried reports of widespread "desperation" among the Afghan rebels, according to western diplomats based in Kabul.

Emboldened by the successes of the summer offensive, Soviet-backed Afghan Army forces have issued a series of ultimatums to prominent resistance leaders to surrender or face another major bombardment.

Reports from a western diplomatic mission in Kabul described the Shomali air raids as the worst since the war began in December 1979, and an Afghan exile source here called the attacks and the subsequent flood of refugees to the capital "unprecedented."

The attacks contrasted sharply with the continued absence of clashes in the normally volatile Panjshir Valley, where guerrillas and the forces of Afghan leader Babrak Karmal have disengaged in what has been reported as a tacit cease-fire agreement.

According to western diplomatic reports from Afghanistan, Soviet helicopter gunships and fighter-bombers last week pounded Charikar, capital of Parwan Province, and attacked a number of villages in the nearby Khayr-Khanah Pass, forcing thousands of refugees to flee to Kabul.

Tanks and artillery batteries stretched for 30 miles along the highway connecting Kabul and Charikar also pounded the Shomali region, after which Soviet-supported Afghan troops in armored vehicles entered the Shakar-Dara and Guldara valleys to search for Afghan rebels, diplomatic sources said.

Residents of the villages were warned against supporting the rebels, and in one village, more than 20 residents who complained about the bombardment were summarily executed, according to the reports from Kabul.

Numerous houses in Guldara were said to have been looted and destroyed by the ground forces.

The western diplomats said the resistance forces were "reeling" from the intensity of the Soviet and Afghan Army summer offensive in the Shomali area, and had become dispirited by the flight of thousands of local residents upon whom they rely for shelter and logistical support.

A guerrilla leader with the Jamiat-e-Islami organization in the town of Fazar, 10 miles from Charikar, was reported to have been given until last Saturday to surrender or face another bombardment.

The western diplomatic sources said in their delayed reports that the rebel leader rejected the ultimatum but was at a loss about how to meet another sustained bombardment.

"For the first time, we detect a note of desperation in the accounts given by travelers from Shomali," a western diplomatic analyst said yesterday.

An Afghan exile leader here said, "The situation in Shomali is taking on very ominous proportions. Each report we get is worse than the one before. They are getting very heavy bombardment."

Rebel units were reported to have fared better in Paktia Province, in southeast Afghanistan, where a large Soviet and Afghan Army force dispatched to open the road between Gardez and Khowst, the two major towns of the province, was stymied in the face of stiff resistance.

According to diplomatic reports, Khowst has been inaccessible to military convoys, and the 25th Afghan Army division there is being supplied entirely by air.

Most of Paktia Province is controlled by the moderate National Movement headed by rebel leader Sayed Ahmed Gailani.

Meanwhile, two weeks of intensive bombing of the city of Herat, in western Afghanistan near the Iranian border, ended last week, diplomatic sources said. They said that "several thousand" civilians were killed in air raids that were carried out by up to 50 aircraft a day. graphics/map: AFGHANISTAN By Richard Furno--TWP western Afghanistan near the Iranian border, ended last week, diplomatic sources said. They said that "several thousand" civilians were killed in air raids that were carried out by up to 50 aircraft a day