Afghan guerrillas turning Soviet attack to their advantage.

The series of offensives launched by the Soviet occupation forces against the Afghan resistance this spring appears to be faltering. Reliable information remains sparse, but according to recent reports, bitter fighting continues to rage throughout much of northern Afghanistan, with the guerrillas holding the initiative in several key areas.

Sources who have recently returned from Afghanistan maintain that the Soviets are still seeking to conduct search-and-destroy operations against the resistance. Confrontations along the strategic Salang highway from Mazar-i-Sharif to Kabul have been described as ''particularly violent.'' Since the beginning of the main offensives, the Red Army high command has been forced to fly in urgently needed supplies, which has seriously hampered its anti-insurgency campaign.

Repeated ambushes by the mujahideen, as Afghan guerrillas are called, are also said to have inflicted heavy Soviet casualties. Western intelligence sources estimate that as many as 3,000 Soviet troops may have been killed throughout the country over the past six weeks.

At the same time, however, Soviet heliborne troops supported by helicopter gunships have caught guerrilla units in devastating cross fire on a number of occasions. The guerrillas have admitted to several hundred dead; civilian losses are thought to be extremely high.

But, as before, aerial attacks against guerrilla fighting in the mountains have not proved very effective. A Western journalist reported that after eight hours of extremely concentrated bombardment, the Soviets had managed to kill only one partisan and wound two others.

Latest reports from the Panjshir Valley indicate that the mujahideen, led by Tajik commander Ahmed Shah Massoud, have temporarily thwarted the seventh Soviet offensive. Launched on April 21, it was said to involve nearly 30,000 Communist troops at its height and backed by armored vehicles, helicopter gunships, fighter aircraft, and high-flying bombers.

In his latest dispatch to Peshawar, Pakistan, the Panjshiri leader said he did not envisage a rapid reoccupation of the valley by his men. ''But it does not matter if the Russians stay a long time,'' he wrote. ''It will cost them a lot, and in the meantime we will spread the guerrilla war throughout the country.''

Mr. Massoud and other sources maintain that guerrilla forces have retaken the nearby Andarab Valley from the Soviets. At present, well-trained ''motariks'' (mobile guerrilla units) operating among the side valleys and 15,000-foot-high mountains overlooking the Panjshir are harassing the Soviets wherever possible.

Reportedly, they have pushed them back down the valley to Bazarak. The Soviets have been forced also to evacuate heliborne commandos previously dropped onto the crests to hold the heights after they were engaged by guerrillas who had crept up during the night.

While much public attention has focused on the Panjshir region, some Western observers in Afghanistan have been particularly struck by the high degree of cooperation and fighting ability among the guerrilla fronts, including Massoud's , in at least six provinces such as Herat, Balkh, and Badakhshan.

''From the areas I have visited and from what I have heard, the mujahideen have turned about the Soviet offensive in many parts and have themselves gone on the counteroffensive. I have never seen morale so high,'' noted Andrew Skrzypkowiak, a free-lance cameraman recently back from the Salang and Panjshir areas.

But, he added: ''The ability among those in the north to sustain present momentum will largely depend on whether enough outside ammunition can be brought in.''

Most northern commanders expect to face severe shortages in the weeks ahead and have called for more mortar, rocket, and rifle rounds. The mujahideen have also specifically requested consignments of gas masks to be sent in view of the Soviets' reported use of gas.

As part of the strategy agreed upon with other regional commanders, Massoud has sought to prevent presenting a single target to the Soviets. His main objective, it seems, is to keep the Soviets as busy as possible on as many fronts as possible.

Coordinating efforts with other local partisans, Massoud has dispatched fighters to Kabul to conduct urban guerrilla attacks and assassinations. Other units have spread out into the countryside to clear out Soviet heliborne commandos and communist militiamen blocking major supply routes to Pakistan.

Life has become much tougher for the civilians, however. This year's military operations are considered the most brutal so far, with the Soviets making little or no distinction in their attacks against guerrillas or civilians.

Although Massoud ordered all civilians to be evacuated before the Soviet offensives, resistance sources and outside observers have reported massive World War II-style raids over the Panjshir and other regions. Believed to have been launched from bases deep inside Soviet Central Asia, rows of high-altitude bombers flying six abreast have once again destroyed countless villages, farms, and irrigation systems.

''The Soviet depopulation of Afganistan is taking its toll. The situation is looking very bad,'' warned Laurence Laumonier of the Paris-based Aide Medicale Internationale. Dr. Laumonier has just returned from four weeks in Pakistan and is in regular contact with French voluntary doctors working in the Afghan interior.

''From what we hear, the situation has deteriorated badly as far as the civilian population is concerned. Many Afghans simply no longer have the means to survive on their own. Much has been destroyed. They desperately need food, clothing, money, and medication . . . little of which is coming through.''