The Defense Ministry said U.S.-backed rebels twice attacked troops Saturday in violation of a government-declared cease-fire, killing two soldiers in one attack and losing four dead in another.

The ministry said in a statement that the rebels, known as Contras, killed two soldiers, wounded one and captured four others in a morning ambush about 90 miles northeast of Managua in the province of Matagalpa.In another incident in a remote region near the Caribbean coast, four rebels were killed when they attacked Sandinista troops, the statement said.