Fighting erupted overnight when some militants opened fire on a check post in the Tanai area of the South Waziristan tribal region, chief military spokesman Major General Waheed Arshad said.

"The miscreants opened fire on a military check post at about 2:00 am (2100 GMT). The troops retaliated and killed three attackers," Arshad told AFP.

The attack in South Waziristan came after a relative lull in the area in recent months.

Local tribes and foreign militants, mostly Uzbeks, fought gunbattles in South Waziristan earlier this year in which scores of foreigners were killed.

The latest attack in the area came amid a spike in violence since last month in the neighbouring North Waziristan region.

Two Pakistani soldiers were wounded overnight as militants fired rockets at the Mana check post near Miranshah, the main town in North Waziristan.

The militants also fired three rockets overnight on Ghulam Khan post, close to the Afghan border, but there were no casualties, officials said.

Violence has escalated in the region since pro-Taliban militants on July 15 scrapped a peace deal with the government, soon after Pakistani troops stormed a radical mosque in the capital Islamabad, killing scores of people.

Pakistan has deployed some 90,000 troops along the Afghan border to hunt down Taliban and al-Qaeda fugitives.

Suspected Islamic militants have recently slaughtered several locals and Afghan refugees after accusing them of spying for US troops operating across the border in Afghanistan.