The Pakistan Taliban on Friday claimed responsibility for a suicide attack near the Afghan border that killed 22 policemen, saying it was their first retaliation for their leader's death.
A suicide bomber got into barracks near the Torkham border crossing late Thursday when officers were preparing to break their fast for Ramadan.
Officials said the attacker triggered explosives strapped to his body, killing 21 people and wounding 15 others. One more died of injuries overnight, they said.
"We claim responsibility for the blast," Azam Tariq, spokesman for Tehreek-e-Taliban Pakistan (TTP), said in a telephone call from an unknown location.
"This is our first response since the death of our chief Baitullah Mehsud," Tariq told news agency AFP. "We will continue similar attacks in the future also."
He said "the victims of the suicide attack were all those supporting the United States. Anybody supporting the U.S. is our enemy."
Feared warlord Mehsud was killed in a missile strike by a U.S. drone aircraft on August 5. His death was confirmed by Taliban commanders on Tuesday.
Thursday's bombing came hours after a U.S. drone attack killed eight people in the nortHwestern tribal area of South Waziristan.
Al Qaeda's number two Ayman Zawahiri called on Pakistanis Thursday to support jihadists in the country's tribal areas, saying it was "the" battle against the American "crusaders", said the U.S.-based SITE Intelligence group.
The statement appears to support Hakimullah Mehsud, a young commander who this week claimed leadership of the Pakistan Taliban.
More than 2,000 people have been killed in a series of bomb blasts and suicide attacks in the country during the past two years.
Pakistan's northwest and tribal areas have been wracked by violence since hundreds of Taliban and Al Qaeda fighters sought refuge there after the U.S.-led invasion of Afghanistan in 2001.