Switzerland announced yesterday that it plans to buy 420 battle tanks from West Germany, spurning the controversial American M1 Abrams tank in one of the M1's first international competitions.

U.S. Army officials issued a statement saying they remain "supremely confident" about the M1, one of the Pentagon's most expensive and most criticized weapons programs.

The Swiss said they would buy $2.1 billion worth of West Germany's Leopard 2 tanks because they are cheaper than the sophisticated M1, performed better in trials and could be delivered sooner.

In addition, the Leopard's manufacturer, Krauss Maffei of Munich, agreed to permit manufacture of the tanks by a licensee in Switzerland, while General Dynamics of St. Louis offered only co-production of some M1 parts, with final assembly in the United States.

The Swiss decision came after the Netherlands had agreed to purchase the German tanks, and followed years of lobbying by both nations in Bern. Although Swiss officials did not mention it in their official statements, U.S. criticism of the M1 received considerable notice in the Swiss media and was thought to have played a role in the decision.

An M1 costs more than $2.5 million, is faster and stronger than any previous U.S. tank but also uses much more fuel than any of its predecessors, and in early tests has broken down far more often.

At numerous hearings, Army officers have said that the problems can be fixed and that the M1 is "the best tank in the world." Still, the Army has been considering seeking a second source of M1 engines, which are manufactured exclusively by Avco Corp.'s Lycoming division in Connecticut.

Avco's production line has been plagued by delays and quality control problems, but company officials say the problems have been resolved.

Congress, led by its Connecticut delegation, voted this summer to prohibit the Army from seeking a second engine source. Complaints about that action from Army Chief of Staff Gen. John A. Wickham Jr. and Defense Secretary Caspar W. Weinberger also were reported widely in Switzerland.

"While the U.S. Army is naturally disappointed that the Swiss government has chosen the Leopard main battle tank over the Abrams, we are pleased to note Swiss praise for the performance of the Abrams and their confidence in its reliability," the Army statement said yesterday.

"The Abrams main battle tank is proving itself in daily service to the U.S. Army, and we remain supremely confident of its ability to satisfy the demands of the modern battlefield."