Seventeen people were killed when communist rebels attacked a military outpost in the southern Philippines Tuesday, an army spokesman said.

An undetermined number of guerrillas swooped down on an army patrol base in Malaybalay City in Bukidnon province, 855 km south of Manila, according to Major Michele Anayron.

Anayron said troops manning the outpost clashed with the rebels, killing 11 of them.

But four government troopers and two civilians were killed in the attack, he added.

'The rebels attempted to overrun our patrol base but they were repulsed,' he said.

The attack occurred two days after the New People's Army, the armed wing of the Communist Party of the Philippines, marked its 40th founding anniversary.

Anayron said the attack could have been a retaliation for troops taking over two rebel camps last week.

Communist rebels have been fighting the Philippine government since the late 1960s, making the movement one of the longest-running leftist insurgencies in Asia.