More than 50 people died in missile strikes by a US drone aircraft in a Taliban stronghold area of Pakistan, officials there have said.
The people killed in South Waziristan had been attending the funeral of a militant commander who had been killed in an earlier strike.
The attack came as the Pakistani army prepared a new offensive in the area.
South Waziristan is the main stronghold of the Taliban leader in Pakistan, Baitullah Mehsud.
One unnamed intelligence official quoted by the Reuters news agency said that Tuesday’s attack happened when people were leaving the funeral of the militant commander.
“Three missiles were fired by drones as people were dispersing after offering funeral prayers for Niazi Wali,” the official said, referring to a militant commander killed in an earlier drone attack.
A military official said the army had no information of the attack.
There have been more than 35 US strikes since last August – killing over 340 people – and most have landed in the North and South Waziristan tribal regions.
Pakistan has been publicly critical of drone attacks, arguing that they kill civilians and fuel support for militants like Baitullah Mehsud.
The US military does not routinely confirm drone attacks but the armed forces and the Central Intelligence Agency (CIA) operating in Afghanistan are believed to be the only forces capable of deploying drones in the region.
In March, US President Barack Obama said his government would consult Pakistan on drone attacks.
In a separate incident earlier on Tuesday, tribal leader Qari Zainuddin – who often criticised Baitullah Mehsud – was shot dead by a gunman in north-western Pakistan.
Earlier this month, Zainuddin criticised Mehsud after an attack on a mosque which killed 33 people.
But Zainuddin’s killing is being seen as a setback for the government, says the BBC’s Mike Wooldridge in Islamabad.
The government is seeking to isolate Mehsud ahead of the security forces’ next phase of their anti-Taliban offensive in the tribal areas bordering Afghanistan, our correspondents says.