Reports of heavy fighting between Afghan guerrillas and Soviet troops in the mountains around Kabul signal a surge of the resistance to the Marxist government of Babrak Karmal and the Soviet military presence that keeps it in power.

While occasional artillery bombardments and infrequent hit-and-run guerrilla attacks occured in areas around Kabul even before the Soviet military intervention late last year, the recent sharp increase in resistance marks the first time since the Marxists took power in Afhanistan 26 months ago that such intense antigovernment activity has ranged in the area of the capital.

The current level of guerrilla activity around Kabul, about 60 miles from Afghanistan's nearest frontier, also seriously undercuts Soviet claims that rebel operations are launched from sanctuaries in neighboring Pakistan and Iran.

Afghan specialists believe most of these insurgents are from interior provinces of the country, including Bamyan west of Kabul and Parwan to the north.

Open resistance so close to Kabul is certain to further embarrass the Babrak government, which has already been forced to put down a students' revolt in the capital during late April and major rioting there in February.

Political analysts discount as "highly exaggerated" estimates that the number of insurgents around Kabul may be as high as 20,000. There is also considerable skepticism among Afghan experts that the appearance of large numbers of insurgents so close to Kabul means that an all-out battle for the capital itself is about to take place.

However, there is very indication that the Soviets are taking the increased rebel presence as a definite threat to the city's security.

In Washington, the State Department said reports from Kabul confirmed fighting in the area outside the city amid increased Soviet convoy movement and flights by helicopters and warplanes. However, there was no way to determine the number of Afghan Moslem rebels involved or the extent of casualties.

["Obviously there is a converging on the vicinity by the rebels, but I doubt that even the rebels themselves know how many they are," a State Department official said. "It sounds as if the fighting is encircling the city, although it's not exactly a siege.]

"Regardless of the specifics, the Russians in Kabul perceive a new threat to the city from outlying areas and have moved quickly to take action," said one area specialist in New Delhi.

Citing reports from the capital, this source said columns of Soviet armor were seen moving out of the city and fighting has taken place in towns surrounding the capital during recent days.

While Kabul itself reportedly remains quiet, diplomatic sources speak of a more visible Soviet presence in the city, mainly after dark.

According to Afghan specialists, not all the military activity around the capital is directed against around the capital is directed against insurgents. One area specialist said there was strong reason to believe a major air attack earlier this month on villages near the town of Paghman about 10 miles northwest of Kabul was retailiatory raid folling the assassination of two Marxist party members by members of a rival party faction.

Afghan experts believe the effectiveness of rebels operating around the capital will be diminished by the recently announced execution of Abdul Majid Kalkani, an important leader of guerrilla insurgents operating in areas north and west of Kabul.

Operating mainly in Bamyan, Parwan and Kabul privinces, Majid is said to have had a small, but well-organized following of about 1,000 to 1,500 followers. Afghan sources here credit him and his followers with playing a leading role in the February Kabul uprising. He was reportedly captured in Kabul by chance during a house-to-house search in late February.