Pakistan's army launched a long-expected ground operation in the troubled North Waziristan region yesterday, hours after jets pounded militant hideouts in the country's northwest.
The Taliban and ethnic- Uzbek fighters holed up in North Waziristan - home to some of Pakistan's most feared militants and Islamist commanders - have both claimed responsibility for the June 8 commando-style attack on Karachi airport.
"On the directions of the Government, Armed forces of Pakistan have launched a comprehensive operation against foreign and local terrorists who are hiding in sanctuaries in North Waziristan," a military statement said.
A military official in the main North Waziristan town of Miranshah said that the coordinated operation - involving airforce, artillery, tanks and thousands of ground troops - had started.
"Thousands of troops will participate in this action. You can roughly say 25,000 to 30,000 troops will be involved in the operation," the official added.
One official said the alleged Uzbek mastermind of the Karachi attack had been killed in the overnight airstrikes.
"Abu Abdul Rehman Almani, who was the mastermind of attack on Karachi airport, and several other commanders have been killed in the strikes," he said.
The military assault targeted the mountainous Dehgan area, some 25km west of the main town of Miranshah in North Waziristan, a stronghold for Taliban and al-Qaeda-linked militants on the border with Afghanistan.
Watch: Taliban make new threats as Pakistani forces deploy
"Today at about 0130 hours, a number of terrorist hideouts in Dehgan, Datta Khel in North Waziristan were targeted by jet aircraft. The number of terrorists killed in early morning strikes has risen to 80," the military said.
Taliban spokesman Shahidullah Shahid, in a an e-mail to media vowed to avenge these attacks, but was not available to provide further details.
There were conflicting accounts of how many people were killed in the air strikes. The military said in a statement that more than 50 militants were killed, although intelligence officials earlier put the toll as high as 100.
"There were confirmed reports of presence of foreign and local terrorists in these hideouts who were linked in planning the Karachi airport attack," the military said.
The area where the strikes occurred is remote and dangerous for journalists, making it impossible to independently verify the accounts.
Residents in North Waziristan said they were woken after midnight by the sound of jets roaring overhead but said the strikes happened in a remote mountainous area.
"All the family members gathered in the yard in fear," said Tawab Khan, a resident of the village of Boyapul, about 8km from where the air strikes hit.
"We could hear big bangs but they didn't come from very close to our area."
The military said most of the dead were Uzbeks. Uzbek militants have long based themselves in the northwestern tribal areas.
The Islamic Movement of Uzbekistan, along with the Pakistani Taliban, claimed responsibility for the airport attack in what was a rare instance of the group striking within Pakistan.
The militant group was formed in 1991 to overthrow the Uzbek government and install an Islamic caliphate there but later expanded that goal to include all of Central Asia. The organisation has attacked US and Nato targets in Afghanistan.
When the jets struck, the militants had been gathering to discuss a deadline given by authorities for them to leave the area, two of the Pakistani officials said.