At least 33 people have been killed and dozens injured in a suicide car bomb attack at a village market in north-west Pakistan, police say.
The explosion is said to have taken place at a busy intersection close to the garrison town of Kohat.
Most of the dead are said to be members of the Shia Muslim minority. The area has a history of sectarian tension.
A little-known militant group calling itself Lahskar-e-Jhangvi al-Almi says it carried out the attack.
It says the attack was in revenge for the death of a prominent religious leader, Maulana M Amin, who was killed in Hangu in June.
Correspondents say the group is likely to be linked to Lashkar-e-Jhangvi, a Sunni extremist group which has links to the Taliban.
ANALYSIS
Aleem Maqbool, BBC News, Islamabad
The Taliban operate widely in Kohat and had at one point warned barber shops in the area to stop giving, what they described as, un-Islamic haircuts.
Pakistan's army has since carried out major operations against the Taliban in the North West of the country and last month a US drone strike killed the Pakistani Taliban chief Baitullah Mehsud.
But there are signs that the Taliban is trying to reassert itself under its new leader Hakimullah.
Astarzai village, where the blast took place, has a substantial Shia population and is close to the Orakzai tribal region, a stronghold of the Taliban's present chief.
Hakimullah Mehsud took over as the leader of the Pakistani Taliban - a Sunni group - after his predecessor, Baitullah Mehsud, was killed by a US missile strike.
The head of Astarzai's village council told the BBC it was still waiting for machinery to help lift the debris and pull out bodies.
"The blast took place at 11am, and now it's 5pm, but there is still no shovel or crane available to lift the debris or pull out dead bodies.
"People are doing it with their bare hands," Mehtabul Hasan told the BBC.
Police officials said that not all of the bodies had been identified because of the extent of the injuries.
Thronged with shoppers
The car bomb was detonated close to a hotel owned by a Shia Muslim businessman.
A local police official told the AFP news agency: "Dozens of shops were destroyed. Their roofs caved in and many people were trapped under the debris."
Television footage from the local hospital showed bloodied and bandaged patients being treated by medical staff.
"I was standing in front of my shop when all of a sudden, a car blew up outside a restaurant," Sohail Ahmed told AFP from his hospital bed.
At the time of the explosion, the area was reported to be thronged with shoppers buying supplies for the weekend and for iftar, the break of fast during the Muslim fasting month of Ramadan.
Astarzai lies 18km (11 miles) west of Kohat, where a bomb was detonated on Thursday wounding at least six people.
NORTH-WEST PAKISTAN BLASTS
18 September: At least 25 people killed in a suicide bombing at a market in the north-west
30 August: Suicide bomber kills 14 police recruits in Swat valley
27 August: 22 police guards killed at checkpoint on Afghan border
14 August: Seven killed in market blast in Dera Ismail Khan
5 June: Mosque blast kills at least 38 in Upper Dir district
20 February: Dozens of Shias killed in market bombing in the north-west
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