( Reuters ) - Pakistani soldiers backed by helicopter gunships killed 20 pro-Taliban militants in an attack on Sunday in the North Waziristan region on the Afghan border, a military spokesman said.
The army attack came hours after staunch U.S. ally President Pervez Musharraf swept the most votes in a presidential election.
"The operation is still on. Militants hold positions in the mountains and we're targeting them with artillery and helicopter gunships," said military spokesman Major-General Waheed Arshad.
Twenty militants had been killed and 15 wounded, he said.
Arshad said the attack was launched after militants ambushed a military convoy near Mir Ali town, 24 km (15 miles) east of the region's main town of Miranshah town on Saturday evening.
Residents of the area had said earlier they had seen a military build-up, apparently in preparation for an offensive against the al Qaeda-linked militants.
Pakistan has seen a wave of violence since July, when a peace pact with militants broke down in North Waziristan and army commandos stormed a radical mosque in the capital, Islamabad.
The violence has reinforced opposition among many Pakistanis to Musharraf's support for the U.S.-led war on terrorism.
Musharraf has said terrorism and extremism are the biggest challenges the country faces and has called for reconciliation among political parties to tackle it.
Waziristan is a hotbed of support for Taliban and al Qaeda militants, who fled to the region after U.S.-led forces drove them out of Afghanistan in late 2001.
Militants in neighboring South Waziristan are still holding about 225 soldiers captured at the end of August.