Local Africans have started calling it the "termite war," as the two sides in this strange conflict - Katangan rebels on one side and a joint force of Zairian and Moroccan troops on the other - slowly eat away each other's territory.

For the first five weeks, the Katangans gradually took pieces of Zaire's southern province of Shaba, until a week ago they claimed a third of the mineral-rich region.

Now the war has turned in favor of Zairian and Moroccan forces who are slowly pushihg their way back into rebel-held terrain. In the past five days they have moved abour 25 miles, from this frontline base over two roads to flank the strategically important bridge on the Lufupa River. They have advanced through a red clay landscape covered with giant termite hills, some as high as 15 feet, - another factor that inspired the Africans' name.

But so far there has been little fighting on either side, according to the Moroccan commanders and a few French officers still offering organizational support here. The Katangans now are retreating as quickly as the Zairians did in the opening stages, according to Zaireian and Moroccan soldiers.

The Zaire News Agency announced tonight in Kinshasa, the capital, that Zaire's forces, including pygmy troops with bows and arrows, had surrounded the Katangan stronghold of Mutshatsha. The News Agency said Moroccan support troops were not far behind.

But at noon here today, the local Zaire army commander, Col. Moboto Ikuku, said his forces were still at least 40 miles from Mutshatsha and it would probably be several days before an advance on the town, which the Katangans are are expected to defend.

Also, the few pygmy members of Zaire's army who have been seen in bases around Kolwezi, Shaba's mining center, have all been well equipped with rifles, often as tall as the small tribesmen.

Observers believe it more likely that Moroccan forces are leading the way, rather than being in the rear. According to Moroccan Col. Mohamed Abdel Ouahad, his troops are plotting strategy for the current counteroffensive and manning the front line positions.

The Moroccans - considered among the best soldiers in Africa - clearly have introduced the efficiency, discipline and organization required in the Shaba operation. In light of the Zaireian army record before the Moroccans arrived, it appears their presence has been an essential factor in the recent advances.

At tonight's press briefing, officials announced that the first two Katangan rebels had been captured and the first enemy equipment and vast sums of counterfeit money - both U.S. dollars and Zairian currency - were found by government troops.

The captured weapons, transported to Kinshasa on a C-130 supply plane, included four aged Belgian rifles and a box of Russian ammunition.

The two alleed Katangans are in their late teens or early twenties and had been wounded in the head or neck. In a brief interview before the plane left Kolwezi one of the barefoot youths, dressed only in peasant trousers, said he was a Katangan of the Lunda tribe. He said that 1,600 Katangans were in Zaire, but that no Cuban forces were supporting them.

He also said after some prompting from a military policeman that his commander was Gen. Nathaniel Mbumba, the reputed leader of the current Katangan rebellion.

There has been growing controversy over the composition of the rebel forces. Missionaries in Kolwezi recently have claimed there are several tribes involved in the operation and that it is indeed an internal rebellion. The government, however, has charged that Cuban troops are providing the strategy and rearguard for rebels operating inside Zaire.

The recaptured territory and the display of prisoners and weapons are the first public boosts for the government of President Mobutu Sese Seko in its efforts to prove the seriousness of the Shaba conflict and to counter, in a small degree, the continued denials of involvement by the Angolan, Soviet and Cuban governments.

News agencies reported these developments elsewhere:

Morocco's forces in Zaire have "absolutely certain" proof that cuban soldiers are among the invaders in Shaba Province, King Hassan II told reporters in Rabat. He said interrogation of a prisoner captured west of Kowezi showed that Cubans and white Angolans were employed in the rebel's command, logistic and training structure.

Meawhile, the first Chinese aid to Zaire arrived in Kinshasa.