Mozambique rebels said Saturday they attacked and occupied army barracks 15 miles from the South African border and killed an undisclosed number of soldiers. The Mozambique National Resistance said it attacked the barracks in Moamba on Tuesday and ``destroyed three battalions of the 2nd brigade'' of the Mozambique army. Moamba is about 30 miles northwest of the capital, Maputo. A rebel statement distributed in Lisbon said the survivors of the attack fled toward South Africa. The statement also denied any responsibility for reported massacres of civilians over the past 15 days. The rebels, also known as RENAMO, have been fighting since 1977 to topple Mozambique's Marxist government.