As violence continues unabated in South Africa, U.S. officials are investigating whether shotguns from the United States have found their way into South Africa, violating the spirit of sanctions against that country.

Authorities are looking at some American companies that have been shipping shotguns and accessories to South Africa. A 1986 U.S. law prohibits the shipment of guns, among other things, to South Africa as a protest of apartheid.

Reports of 1990 U.S. exports show that at least three companies shipped guns or accessories to South Africa -- Jonas Aircraft and Arms of New York, Nosler Bullets of Oregon and Mossberg International of Connecticut. Jonas and Mossberg manufacture guns. Nosler makes bullets for sporting rifles. All three have told federal authorities that the guns were shipped through Cape Town, but that the final destinations were other countries. Nosler and Jonas told us their shipments went to Zimbabwe. Mossberg officials were not available for comment.

In the past four years, various U.S. manufacturers have shipped more than 50 tons of arms through Cape Town, claiming that all the shipments were headed for Zimbabwe.

Zimbabwe is landlocked, so goods being shipped there must be unloaded at some African port, but Cape Town is too close for comfort for anti-apartheid activists. They believe sloppy enforcement of the embargo makes it too easy for the guns to stay in South Africa or be slipped back in after arriving in Zimbabwe. The gun makers say they have no control over what happens to the guns once they are in the hands of buyers in Zimbabwe.

Anti-apartheid activists suspect that the shotguns, designed for game hunting, are turned against South Africa's blacks. Recent violence has justified their fears. In November, reports surfaced of an attack by white extremists on black mine workers near Johannesburg. The whites used a variety of weapons, including shotguns.

"We think it would be tragic for people who have survived apartheid to stand the risk of being killed by American arms," Dumisani Kumalo of the American Committee on Africa told us.

Our associate Scott Sleek has learned that export enforcers at the Commerce Department are investigating where the guns ended up.

Sanctions have been compromised before. For example, the United States imported $350 million worth of South African steel in 1987 and 1988, despite the sanctions law. South African clothes and food find their way to the United States, and oil goes the other way. Vague language in the sanctions law and lax enforcement have allowed the United States to remain one of South Africa's biggest trading partners.

That's not likely to change. The global criticism of South Africa is abating. The European Community recently voted to start lifting its sanctions, and the United States could follow suit.

The reason for the new attitude is President Frederik W. de Klerk, who has vowed to eliminate racism in South Africa. But so far, apartheid has only been modified. It is too soon to start rewarding the government in a big way for small steps.