Taliban militants in Pakistan's North Waziristan tribal region along the Afghan border say they are abandoning a months-long truce with the government.
Although U.S. drone airstrikes have regularly targeted militants in the region, the unpublicized peace deal had greatly reduced hostilities in the Taliban-dominated area.
But on Tuesday, a spokesman for a local militant faction, Ahmadullah Ahmadi, said the ongoing U.S. strikes and Pakistani army operations in North and South Waziristan have prompted the Taliban to end the agreement.
The collapse of the agreement comes weeks after the Pakistani military began its campaign to hunt down Taliban leader Baitullah Mehsud in neighboring South Waziristan.
Meanwhile, news reports in the United States say Washington and Islamabad have increased intelligence-sharing in the tribal area offensive.
The New York Times newspaper reports U.S. surveillance aircraft several weeks ago started providing the Pakistani military with live video and other information on militant activities in the region.
The newspaper says the Obama administration is also speeding the delivery of transport helicopters, body armor and other equipment to help Pakistan's military take on Taliban militants entrenched in the rugged border region.
Pakistani and U.S. officials have not publicly confirmed the alleged arrangement.
While Pakistani jets have pounded militant positions in Waziristan in recent weeks, troops continue to pursue militants in the greater Swat valley. On Tuesday, the military said 18 suspected militants had been killed and 23 others detained in the last 24 hours. A military statement said three soldiers were killed and eight others injured in the fighting.
In Pakistan's southwest, local police say four people died when a car bomb exploded near a route frequently used by trucks carrying NATO supplies into Afghanistan.
Tuesday's bombing in Baluchistan province wounded five other people. No one has claimed responsibility.
Militants have frequently targeted supply lines for the U.S.-led coalition, which uses two major routes in Pakistan. Most attacks have occurred at the northwestern Khyber Pass route.