At least 18 soldiers were killed and 28 others wounded when a homicide bomber struck a military convoy with an explosive-laden vehicle in northwestern Pakistan on Saturday, an army spokesman said.

The attack happened on a road near Daznaray, a village about 30 miles north of Miran Shah, the main town in North Waziristan, said Maj. Gen. Waheed Arshad. The army spokesman said the dead and wounded were being transported to a hospital.

Two local security officials said the attack had killed 12 soldiers, with another 20 troops wounded. The officials, who spoke on condition of anonymity because of the sensitive nature of their job, did not provide further details, saying authorities were investigating the incident.

The turbulent tribal region is a haven for local and foreign militants, and has been the scene of scores of military operations against remnants of the Taliban and Al Qaeda after Pakistan became a key ally of Washington in its war on terror.

Pakistan has dispatched thousands of troops to other areas of the northwestern frontier to pressure outlawed Islamic militants preparing to launch a holy war against the government for its bloody attack on Islamabad's Red Mosque, military officials said Saturday.

A spokesman for militants in North Waziristan demanded the military remove all checkpoints from the region by Sunday.

Abdullah Farhad, who claims to speak for pro-Taliban militants, told The Associated Press the checkpoints violated a 2005 peace accord between the government and tribal elders.

Although the peace deal is still in effect, militants have again started attacking government forces in the region, while the government has targeted some militant hideouts.