Pro-Taleban militants in Pakistan's North Waziristan region say they have ended their truce with the government.
In a statement issued in Miranshah, the main town, the militants accused the government of breaking the agreement.
It came as Pakistan deployed more troops in the area, fearing "holy war" after the storming of the militant Red Mosque last week left 102 dead.
More than 60 Pakistanis, including soldiers and police recruits, have died in three attacks in the past two days.
Last September's truce had ended two years of clashes and was aimed at stopping cross-border attacks into Afghanistan.
"We are ending the agreement today," the Taleban Shura or Council said in pamphlets distributed in Miranshah, the capital of North Waziristan.
The council leaders released the statement on Sunday amid growing tension in the area.
In a second consecutive day of violence at least 11 Pakistani soldiers - and three civilians - were killed in the Swat area of North West Frontier Province.
Two suicide bombers rammed cars into a convoy - as a roadside bomb also went off.
Another 40 were injured in the attack near the town of Matta, local police said.
In the city of Dera Ismail Khan, in the same province, at least 26 people died in a blast at a police recruitment centre.
More than 30 were wounded when a suicide bomber blew himself up among young men waiting to take a police recruitment exam.
On Saturday, a suicide attack on an army convoy near the village of Daznary, about 50km (30 miles) north of Miranshah, killed 24 and wounded at least 30.
The area is well-known as a stronghold of pro-Taleban militants, police said.
The 102 dead in the Red Mosque (Lal Masjid) siege included 11 soldiers and an as yet unknown number of extremists and their hostages.
The government has sent thousands of new troops to the north-west fearing there could be a new "holy war" in revenge.
Many of the militants in the Red Mosque complex were thought to have come from the north-west.
"The attacks in Swat and D I Khan could be linked to the Lal Masjid," Interior Minister Aftab Sherpao told Geo TV.
"It's very difficult to stop suicide attacks."
President Pervez Musharraf last week vowed to root out extremists "from every corner of the country".