Sarbandki, Pakistan ? A battle between Pakistani security forces and suspected Islamic militants firing rockets and assault rifles left 21 dead Tuesday in a tribal region near the Afghan border.

The fighting was the latest in a spate of violence that has racked the mountainous region in northwestern Pakistan, an area where fighters linked to the al-Qaida terror network are believed to have taken refuge. In four clashes since Saturday, a total of 42 people have died.

The latest casualties came as militants fired rockets at a mountaintop military post in Sarbandki village in North Waziristan, a Pakistani official said on condition of anonymity. Troops returned fire, and the fighting continued intermittently for hours. Fourteen suspected militants – including a local commander – were killed in the clash.

Pakistan has placed about 70,000 troops and paramilitary forces along its border with Afghanistan to weed out alleged al-Qaida and Taliban sympathizers and extremists.