The following dispatch was filed from New Delhi after Americancorrespondents were expelled from Kabul.

Afghanistan's new Soviet-installed government today expelled American journalists on charges of "interference" in the country's internal affairs and "biased reporting."

The expulsion order, first set in motion Wednesday and officially announced to reporters Thursday, could not immediately be carried out because bad weather closed Kabul Airport. In the meantime, U.S journalists were placed under a loose, haphazardly enforced house arrest at the Kabul Intercontinental Hotel.

The announcement of the expulsion Thursday coincided with reports of Soviet shelling about five miles northwest of Kabul Airport. Explosions and shooting also were briefly heard from the vicinity of Kabul's Bala Hissar Fortress, but there was no sign of any serious fighting in the capital itself and residents were conducting business as usual.

Eighteen American journalists were expelled by the government order, including correspondents from The Washingotn Post, New York Times, Los Angeles Times, Chicago Tribune, Boston Globe, United Press International and the three major U.S. television networks.

Most of the 18 flew out today aboard flights to Frankfurt and New Delhi. Some U.S. news organizations continued to be represented in Kabul by non-American journalists, who apparently were not covered by the decree.

For the first time since last month's Soviet-led coup and invasion of Afghanistan, explosions resounded through the capital for nearly three hours Thursday morning and briefly at night. The loud booms were heard again intermittently around midday Friday, although they were muffled by a low cloud cover and steadily fallng snow that blanketed the city and closed the airport.

The new government under President Babrak Karmal offered various explanations for the explosions. The state-run radio assured the public that the booms were merely blasing for a new water pipeline in a Kabul suburb. The radio did not explain why blasting resumed at night.

Foreign military analysts said the explosions sounded like tank or artillery fire, punctuated by an occasional bomb.

Diplomatic sources reckoned the explosions were coming from behind a line of mountains north of the city near the villages of Taraquhel and Paymandan. They said the villages lie on a populated plain and have been the source of Moslem rebel activity in the past.

Western diplomats said they had received reports that there were fighting in the area between Soviet troops and Afghan Moslem rebels or renegade Afghan troops. The sources speculated that Soviet gunners were hammering a stronghold of the Afghan guerrillas, who have been battling a succession of Marxist governments here since the spring of 1978.

The souces said they doubted the loyal Afghan government troops by themselves were currently capable of carrying out a major campaign against the rebels, and they dismissed the idea that the explosions were target practice, because the area is populated.

Asked to guess what the explosions meant, in the absence of any hard information, military analysts said the Soviets "were probably pounding a village into dust."

[The State Department yesterday said two eyewitness reports confirmed accounts Thursday of fighting in Kabul between Soviet troops and regular Afghan Army units, as well as Moslem rebels.]

It was not possible to visit the scene of the shelling because of its inaccessibility to passenger cars and because of Soviet encampments in the region surrounding it.

An American reporter who slipped the Afghan government's house arrest Thursday and drove north on a paved road west of the shelling saw increased Soviet security and surveillance in front of their roadside encampments and truck parks, but no sign of any fighting.

For the first time, Soviet military police in black uniforms were visible at two checkpoints with motorcycles and sidecars. More Soviet soldiers stood guard along the road than a few days previously, but their number -- about 20 in front of the main encampment a few miles north of Kabul -- did not indicate more than a heightened state of alert.

At the suburb of Khai Khana north of Kabul, a line of 30 to 40 Soviet tanks could be seen dug in along the slopes of the mountains separating Kabul from the plain believed to have been the scene of the shelling.

The tanks, part of a defense perimeter the Red Army has set up around the capital to ensure the survival of Moscow's handpicked government, did not appear to be the source of the firing.

Inquiries by journalists into Soviet military activities were believed to have been a major irritant leading to the expulsion order for U.S. correspondents.

The Afghan government said it had decided to expel the Americans because of "continued interference in the internal affairs of Afghanistan and continued biased reporting." An information ministry offical acknowledged privately that a similar move by Iran a week ago has influenced the Afghan decision to single out Americans.

In line with Soviet policy in the region, the new government in Kabul has been trying to curry favor with Iran's Islamic regime under Ayatollah Ruhollah Khomeini. Observers here said the Soviets apparently hope that some of the aura of Iran's Islamic revolution will rub off on Afghanistan and help defuse the Moslem rebellion here.

In an indication of the new government's disorganization, an initial attempt to begin implementing the order turned into a farcial scene.

A minor Afghan police official arrived around 8 p.m., Wednesday at the Intercontinental Hotel, where most noncommunist western journalists have been staying to round up all American passports. The Afghan official left briefly and a crowd of journalists gathered.

When he returned, the bewildered Afghan official was greeted at the door by bright arc lights and TV cameras. As he waved his arms for the TV crews to turn off their lights and cameras, a plainclothes hotel agent came to the rescue by throwing his blanket-like cloak over the official's head and shoving them toward the door.

Then, apparently deciding such an exit was some what undignified, the official suddently turned, threw off the cloak and marched into the manager's office, refusing to come out while the TV equipment was still there.

U.S. consular officials who had arrived in the meantime persuaded the official to take up the matter the following day through diplomatic channels, and the Afghan government instructed U.S. journalists to remain in the hotel.

A pair of Afghan military officers and an assortment of plainclothes secret police agents kept watch on the hotel's main entrance, asking the nationality of persons leaving. However, the guards often left the entrance unattended when they disappeared for tea or meals.

In the case of some of the guards, their hearts did not seem to be in their work anyway.

One plainclothes agent confided that he did not like the Soviet military presence in Afghanistan. He also made clear that he did not care too much for the government of Babrak Karmal.

"We want a national government made up of real Afghans," he said. "We don't like foreigners running our country. But anyway, we like American people more than Russians."