A convoy bringing food and fuel to Kabul broke through a guerrilla blockade Friday, with Afghan soldiers and helicopter gunships providing cover as the trucks rolled down the Salang Highway.

The government said another major highway was reopened Friday, allowing trucks to carry supplies to Jalalabad, which has been under rebel fire for more than five weeks.Fighting continued on the Salang Highway for nearly two hours, and thick, black smoke billowed from the mountains a few miles away. The highway, a vital supply route leading into the deprived capital, was closed a week ago by Moslem guerrillas who are hoping to starve the city into surrender.

The convoy comprised up to 100 vehicles. As it moved slowly down the highway, soldiers fired from tanks and machine gun posts into the surrounding mountains, where the guerrillas are hiding.

Several trucks appeared to have been damaged and one was carrying several wounded men. Diplomats who spoke on condition of anonymity said about 600 trucks were still stranded along the Salang.

Another convoy moved out of the capital and down the highway linking Kabul and Jalalabad, a provincial capital about 70 miles away.

The government said the convoy took supplies to government soldiers who had been depending on air drops. The road, which also is used to ferry supplies to Kabul, was closed to routine traffic almost two weeks ago.

The guerrillas say they control about 20 miles of the highway, the major route to the border with Pakistan.

The guerrillas have made blockades a primary tactic in their fight to overthrow the Marxist government, which seized power in an April 1978 coup.

The Soviet Union has been flying food and military equipment to Kabul. Supplies also are being flown to Jalalabad and Khost, said one senior Soviet source, speaking on condition of anonymity.

The source said about 2,000 government troops had died since the guerrillas began bombarding the city. He said 8,000 rebels had been killed in retaliatory strikes.