The Soviet Union continues to move troops and equipment into Afghanistan in an apparent effort to transform the Soviet airborne division that seized control of the Afghan capital Dec. 27 into a long-term occupation force for the entire nation.

Soviet troops and new equipment were visible today in rural areas up to 50 miles away from Kabul, where the Soviets have in the last three days carefully stayed as far out of public view as possible in an effort to avoid inflaming what seems to be a largely resentful Afghan population.

"Nobody moves in an army this size for temporary reasons," one Western diplomat said here, speaking of the estimated 30,000-40,000-strong Soviet expeditionary force whose arrival during the last week has triggered a major U.S.-Soviet confrontation.

So large a force "is completely inappropriate for a political solution" to the guerrilla war that Afghan insurgents have fought against three successive Soviet-backed governments in Kabul and that the rebels have vowed to continue, the diplomat said.

Long lines of Soviet trucks and other equipment could be seen yesterday moving out of Kabul toward Bamian, west of Kabul, where heavy fighting has been reported involving Soviet units and the Afghan insurgents.

The Soviet equipment moved into Afghanistan across the northern border of this mountainous, landlocked country includes a wide variety of armored vehicles -- among them T72 tanks -- heavy artillery, field kitchens, ambulances, sophisticated, first-line antiaircraft guns, and small mobile radar units used in conjunction with surface-to-air missiles.

The Soviet invasion apparently has shattered the Afghan Army, prompting many Afghan soldiers to defect to the rebel side. This has resulted in clashes between Soviet units and the defecting Afghan troops, diplomatic sources said.

Today, almost all of the Afghan soldiers this correspondent encountered at roadblocks near Kabul and further out in the countryside were unarmed.

Many of the Afghan troops apparently loyal to the new government and seen manning the roadblocks, driving around Kabul or lounging at roadside garrisons, appeared to be disorganized as well as without weapons.

The roads between Kabul and the Soviet border are still clogged with Soviet supply trucks and armor, witnesses said. Last night, a long Soviet troop convoy could be seen wending its way out of the capital, apparently as part of the redeployment effort.

While no organized resistance to the Soviets has emerged yet in Kabul, there are unconfirmed reports that as many as 10 to 15 Soviets have been killed in isolated shooting incidents in the city in the week since the coup. There are also reports of brutal Soviet responses to attacks by Afghan civilians on the Soviet convoys that streamed south across the Afghan border in a three-pronged invasion that immediately followed the strike by the airborne units in Kabul.

According to one account given separately by three Afghans, residents of the village of Kalakon, about 15 miles north of Kabul near the main road to the capital, knocked out at least one Soviet tank. In reprisal, the Afghans said, the Soviets shelled the village Sunday, destroying a number of homes and causing heavy casualties. It was not immediately possible to verify these reports.

A large number of last week's initial invasion force was composed of Soviet troops of Uzbek and Tajik ethnic origin, who share language and culture with residents of those regions of northern Afghanistan. More recently, however, more troops of Soviet European extraction have been seen.

Details of the Soviet overthrow of president Hafizullah Amin and his replacement with Babrak Karmal last week remain sketchy. Informed sources said today, however, that Amin's wife and children had died with him, either by execution or in the heavy fighting that accompanied Karmal's takeover. These sources said Karmal arrived in Afghanistan in a Soviet transport aircraft last Friday, a day after the coup.

In what was described as his first appearance in public since the coup, Karmal thanked Moscow for sending troops to his country at a press conference in Kabul Friday, the official Soviet news agency Tass reported in Moscow.

[The Soviet Union had acted "in defense of the national independence, sovereignty and territorial integrity of Afghanistan," Tass quoted Karmal as saying.]

After overpowering Afghan Army forces in pitched battles at the time of the coup, the Soviets appear to have encountered relatively little resistance. tSome fighting between Soviet forces and Moslem insurgents has been reported, but it does not appear to be as widespread as claimed by Afghan rebel spokesmen outside the country.

The capital is largely quiet, although palpably tense. Most stores and offices are open, but fewer people appear on the streets than before the Soviet invasion, residents say. An 11 p.m. to 5 a.m. curfew is in effect, but gunshots have been heard at Soviet installations nearly every night since the coup.

According to Afghan and foreign sources, the greatest resistance to the Soviets is in Badakhshan Province in the northeastern corner of the country and PAKTIA province in the southeast. Rebels outside the country claimed today that their forces ambushed a Soviet convoy near Bamian west of Kabul.

Diplomats disputed rebel assertions of fighting in Jalalabad, a city east of Kabul seized by a Soviet force in the last two days. A trip through the city today showed no sign of any fighting.

Other cities taken by the Soviets, diplomatic sources said, include Herat in the west, Mazar-i-Sharif in the north and Kandahar in the south. Soviet forces also control the main air base at Bagram north of Kabul and the Shindand air base in the west. Informed sources said Afghans initially put up resistance in Herat, but that it was quickly overcome.

In Kabul, Soviet soldiers in winter gear no longer patrol the streets and guard intersections as they did immediately after the coup. Most have been positioned outside the city, but armored contingents continue to hold key installations such as the radio and television station, the People's House presidential palace in the city center and the Durulaman Palace outside Kabul -- all scenes of fierce fighting during the coup. In addition, the Soviet units guard the Prime Ministry and Interior Ministry buildings. t

At the radio-TV station, Soviet light tanks airlifted in to spearhead the Dec. 27 assault on the building, could be seen in a large courtyard, their barrels facing the U.S. Embassy located just across the narrow street.

After quickly securing Kabul a week ago, the Soviets set up roadblocks at each of the city's half dozen exit roads and began establishing camps and tank and artillery positions all around the city. Some troops reportedly have moved into barracks formerly occupied by Afghan soldiers.

About six miles east of the capital near the exits to the Kabul Gorge, Soviet soldiers yesterday were digging trenches along a ridge overlooking the road.

The array of equipment brought in by the Soviets and their redeployment in the countryside have led observers to conclude that Moscow is determined to crush the opposition by force. One possible motive often cited here is the risk that any overthrow of Afghanistan's communist government could incite the Moslem population of the Soviet Union's own Asian republics.

Since the poorly equipped and badly disorganized rebels have no air power and no chance of getting any, some diplomats suggest that the Soviet antiaircraft capability is here as a precaution against the possibility that the entire armed forces unit might turn on the invaders.

The Soviet wish to keep the lowest possible profile applies to securing villages along their overland supply routes from the north. At Pule Khumri, about 90 miles north of Kabul, Soviet troops were not inside the village but had dug in around it with guns facing the town, one traveler said.

"Everybody was happy that Hafizullah Amin was killed," one senior Afghan civil servant said. "But nobody wants the Russians to occupy our country."

According to diplomats and other sources here, his attitude is shared by many bureaucrats who suffered under the toppled president, but fear that things will be worse under the new Soviet-dominated leadership.

"I am ready to go and join the rebellion," said another government official.

He said that several members of his family have been jailed, tortured or killed since the 1978 communist takeover. Now, he said, he fears that he, too, eventually will be purged.

By all accounts, Kabul residents place little confidence in pledges by the new head of state Babrak, as Karmal is called here, to end the reign of terror begun by Amin when he overthrew Nur Mohammed Taraki in September.

"Afghans as a whole are very angry about what's happened," one diplomat said. He cited the main source of resentment as the Soviet power play to install Karmal.

"Had he done it by himself, he would have been greeted with garlands," said another.

Karmal's lack of any significant popular support appears likely to force the Soviet Army to become a long-term political prop, analysts said.

"To withdraw in the near future will probably result in the collapse of the regime, since it is perceived as being no different from the previous one," one said.