Antigovernment forces in Mozambique continue to receive arms and supplies from South African sources and have spread their campaign to all 10 of the country's provinces despite the nonaggression pact signed by the two countries 10 months ago, according to officials and diplomats here.

In recent weeks, Mozambican officials have charged, rebels of the Mozambique National Resistance Movement have been resupplied by airlifts from South Africa's Transvaal Province, Malawi and the Comoro Islands. Last week antiaircraft gunners at the Caborra Bassa hydroelectric project in Tete Province fired on two light airplanes that officials said were making supply runs from Malawi to rebels in the remote northwestern province.

The resistance movement has used these supplies to help spread its war against Maputo's socialist government into all 10 of Mozambique's provinces this year. The rebels have been increasingly active in Nampula, Zambezia and Cabo Delgado, northern provinces that form the country's agricultural heartland.

The insurgents also have launched a highly visible campaign of economic sabotage and terror in Maputo Province, an assault that began only days after the signing of the so-called Nkomati accord last March 16. Rebel units believed to total between 1,000 and 1,500 men have staged bus ambushes inside the province, killing at least 38 civilians in the first half of this month and virtually cutting off ground transportation to the capital.

Colin McCord, an American doctor at Maputo General Hospital, said the hospital has been treating as many as 100 civilians a month since October for wounds suffered in resistance movement attacks.

Fueled by men and arms that Mozambican intelligence officials charge were ferried into the province in the weeks before the pact was completed, the rebels have staged attacks within 10 miles of the capital. Electric power lines from South Africa to Maputo have been cut five times since October.

Officials here contend that both the electricity sabotage attacks and last week's slaying of two British subjects on the road to Maputo were carried out by rebels who use the Transvaal as a base.

Observers here stress that despite the increase in attacks, the rebels appear nowhere near seizing the capital or taking power in Mozambique. But while Mozambicans remain calm, there is a increasing mood of panic here among foreigners, heightened by a new wave of rebel attacks against foreign workers in the countryside.

In the past, the rebels captured foreigners but treated them reasonably well and eventually released them. In recent weeks, however, they have killed at least 13, prompting the government to inform foreign embassies here last month that it was considering new, unspecified steps to protect foreign workers. Several embassies, representing both western and Soviet Bloc nations, have ordered their workers to pull out of rural areas, as have several United Nations agencies.

The Nkomati accord pledges both South Africa and Mozambique to eliminate any activities inside each country's borders aimed at subverting the other. To demonstrate its commitment to the agreement, Mozambique has expelled more than 300 members of the African National Congress, the antiapartheid resistance movement, who had been living here.

Mozambican officials say they believe South African President Pieter W. Botha and Foreign Minister Roelof F. (Pik) Botha sincerely want Nkomati to succeed. But they say other elements in the South African government, especially in the military intelligence unit that had supplied the resistance movement with arms, training and logistical support since at least 1979, are continuing to aid the rebels. They also say South African citizens of Portuguese descent, who fled to South Africa after Mozambique gained its independence in 1975, are helping fund and arm the movement.

Mozambique wants South Africa to crack down on all these groups and has expressed surprise and disappointment that Pretoria so far has been unable or unwilling to do so.

South African officials have denied the rebels are receiving any support from their government, and President Botha warned last week he would take strong action against anyone found aiding the rebels from inside South Africa.

Meanwhile, official South African sources have been leaking to journalists and Mozambican officials information implicating individuals in other nations, including Portugal, which is Mozambique's former colonial ruler, Oman, Saudi Arabia and the Comoros, in arms shipments to the resistance movement.

Knowledgeable Mozambican sources say the movement has diversified its sources of supply since Nkomati, moving fewer goods and men from the Transvaal and more from other places. In August, four Portuguese citizens were arrested in neighboring Tanzania and charged with seeking to set up clandestine air bases to move supplies into northern Mozambique.

Two such bases are believed to operate inside Malawi, where the conservative government of President Hastings Banda has cool relations with Maputo despite last October's state visit by Mozambican President Samora Machel.

The Machel government has accused Portuguese businessmen who had major holdings in Mozambique before it became independent and even some members of Prime Minister Mario Soares' government of aiding the rebels. Portugal has denied this strongly but has taken no overt steps to shut down resistance movement activities in Lisbon, which reportedly include recruitment of Portuguese mercenaries to fight in Mozambique.

But while officials here denounce what they call "the Portuguese connection," they emphasize their view that the main support for the movement still comes from sources, either official or private or both, inside South Africa.

"We have made no mistake," said Machel in a speech late last month. "South Africa is still the key to the problem and it was for this reason that we signed the accord of Nkomati with it."

Despite its disappointment with South Africa's apparent failure to comply fully with Nkomati, Mozambique does not appear ready to denounce the accord although some hard-liners in the ruling Politburo are said to be lobbying for such a move. Observers believe Mozambique's options are few: Machel is said to be staunchly opposed to issuing an appeal for additional outside troops either from his allies in the neighboring front-line states, or from the Soviet Bloc.

"We do not want to internationalize this conflict or make it an East-West issue, because then we will become like the Middle East and lose control of our own sovereignty," said a knowledgeable official. But he stressed that Mozambique's patience, and its ability to hold out, were limited.

For now, officials here say they will continue pressuring, cajoling and pleading with South Africa to do more to enforce the accord. Their view remains, as one observer put it, "Nkomati so far is a failure, but not a mistake."