The Zaire air force has begun a bombing and rocket campaign against four rebel strongholds in southern Shaba Province in an attempt to rout some 1,500 Katangan invaders.

The Zaire chief of staff, Capt. Gen. Bumba Maso Djogi, said here today that bombing attacks began four days ago, at Dilolo, Kasaji, Sandao and Kisenge. The munitions include American-made 2.75-inch rockets.

It is questionable how effective the bombing can be. The Katangan invaders so far have used guerrilla tactics, operating after dark, which makes it almost impossible for the aircraft to spot them. The area is dense with forests that provide easy cover for rebels who know the territory well.

The small-scale air attacks, done from French-made Mirage 5 attaack jets and Italian-made Macchi counterinsurgency jet fighters, are possibly an effort the Zaire government to compensate for its army's inadequate manpower and arms in the remote area.

[A jumbo jet loaded with about $1 million worth of emergency U.S. aid arrived in Zaire, State Department officials said. U.S. officials have said that the shipment and a similar one last week include spare aircraft parts, medical supplies, parachutes and uniforms but no weapons or munitions.]

[Munitions have been supplied to Zaire by the United States in the past, officials at the State Department and Pentagon said, with only the customary restriction that they not be passed on to another country without U.S. permission.]

So far, the main military impact of the bombing on the rebels, who are far more experienced in warfare than the Zaire forces because of 17 years of combat in Zaire and Angola, appears to be psychological.

Local residents - black Africans and Europeans - believe the Katangans will be able to stay in the small south-eastern section of Shaba Province until the Zaire army is able to introduce counterinsurgency tactics and fight the rebels on the ground.

[Angola today accused Zaire planes of bombing three Angolan towns last week. Shilungo, Shilumbo and Camafuafa, near the Zaire border, were bombed on March 15 and 16, an Angolan Defense Ministry communique said adding that Angola "would not tolerate for very long attacks on its populations."]

The Zaire pilots of two Macchis based at Kolwezi, the region's mining center some 50 miles from the front lines, said they were hitting Kasaji this morning with Spanish-made 110-pound bombs and U.S.-made 2.75-inch rockets.

Bullet holes in the belly of one of the planes indicated it had been hit by ground fire from the rebels.

Since their first attack March 8, the rebel forces have moved slowly toward Kolwezi along the road next to the Benguela railway line, according to army officials. Loss of control of even a small section of this province - rich in copper, cobalt, manganese, gold and other minerals - would be a disastrous blow to Zaire's already troubled economy.

Both Macchi fighter pilots said in answer to questions this morning that they had seen no indication of any activity by rebels near Kasaji. One pilot added that the apparently well-coordinated Katangan supply lines from bases in neighboring Angola could not been seen even during daylight.

Military supplies for Zaire forces in the Kolwezi region must come by air from Kinshasa, the capital - a distance equal to that of New York to St. Louis. Aviation fuel is in short supply in Zaire.

Defense of all the vulnerable borders of Zaire - a country the size of the United States east of the Mississippi - stretches the 25,000-man army thin even in normal times. The central government also has about 35,000 national police.

A serious attack requiring mobilization of troops to remote areas while leaving forces to watch other flashpoints creates strategic and logistical problems.

Gen. Bumba said today that before March 8, this area - long considered to be highly vulnerable - was patrolled by police only.

Bumba said he expected the new bombing campaign would quell the rebellion within a week, but observers were skeptical.

In Kasaji, at least, the bombing apparently has not accomplished its purpose. Zaire President Mobutu Sese Seko announced during a five-hour tour of the area Saturday that his troops had retaken Kasaji, but Bumba, the two fighter pilots and Mayor Muzila Ganda Mandungu of Mutshatsha, a front-line town, all said today that Katangan guerrillas were still holding Kasaji.

President Mobutu dismissed denials by Cuban President Fidel Castro that Cuban troops were involved in the invasion of Shaba. Mobutu said the invaders "are in fact led by Cubans" and were using "the same sophisticated Soviet weapons" used by the 14,000 Cuban forces in the Angolan civil war.