On Monday, army spokesman Maj. Gen. Athar Abbas said the weekend ambush was unprovoked and warned the government reserved the right to retaliate, specifically against tribes that harbor militants. Abbas was not available for comment Tuesday about the scrapping of the deal.

The U.S. has frequently launched missile strikes in North and South Waziristan, attacks American officials say have killed several top al-Qaida fighters.

Pakistan publicly protests the strikes as violations of its sovereignty, though many observers suspect the two countries have a secret deal allowing the strikes.

Pakistan's armed forces are gearing up for a major military offensive in South Waziristan, a hotbed for al-Qaida and Taliban fighters. The region is the main base for Mehsud, who is blamed in numerous suicide attacks in the country and has been accused in the killing of former Prime Minister Benazir Bhutto.

Troops also are pursuing an offensive in the northwest's Swat Valley following the breaking down of a peace pact there. The army says it has killed around 1,600 militants in Swat and surrounding districts in the past two months.

Tuesday's deadly car bombing also wounded five people outside a roadside restaurant where it detonated in Pakistan's southwest Baluchistan province, police said. Area police chief Nazir Ahmad Kurd said the blast took place in Sohrab town, some 190 kilometers (118.07 miles) south of Quetta, the provincial capital.

It appeared to be a remote-controlled blast, Kurd said.

No one immediately claimed responsibility for the explosion, but Baluchistan has long been the scene of a low-level insurgency by ethnic nationalist groups seeking more autonomy for the province.