Flags are flying at half-mast across Pakistan, as the nation marks three days of mourning for the 162 people, most of them children, killed in a brazen attack on a school in the northwestern city of Peshawar.

Prime Minister Nawaz Sharif called a multi-party conference in Peshawar on Wednesday to discuss the state response to the attack, the worst in Pakistan's recent history, which will be attended by leaders across the political spectrum.

During the meeting, a years-long moratorium on the death penalty in the country was lifted, with an official from the prime minister's office telling Al Jazeera that Sharif "approved abolishment of the moratorium on execution of death penalty in terrorism related cases."

Also on Wednesday, Pakistan Army Chief Raheel Sharif was in the Afghan capital Kabul to hold top-level security talks with Afghan President Ashraf Ghani and the commander of ISAF.

Mullah Fazlullah, the chief of the TTP, is believed by Pakistani intelligence services to be operating from Afghanistan's Kunar or Nuristan provinces.

Al Jazeera's Asad Hashim reports from Islamabad:
The attack yesterday was condemned across the political spectrum, but it's not clear whether that will translate today into a unified political stand on what should be done to stop the TTP.
Prime Minister Sharif will be looking to establish a consensus during the multi-party conference, especially with those parties that have opposed military operations against TTP fighters in the past, such as Imran Khan's Pakistan Tehreek-e-Insaf.

Meanwhile, funerals are being held today across Peshawar, as families prepare to bury their children and the nine staff who were killed in the attack.

The Pakistani Taliban (TTP) issued a statement saying only the "adult sons" of military personnel and members of the military had been killed in the raid. The statement included photographs of dead children the group claimed had been killed during military operations in tribal areas.

The group, which had previously justified the attack by saying it was revenge for ongoing airstrikes on areas including northern Waziristan, warned civilians to distance themselves from security personnel or be killed alongside them.

All 132 children killed in Tuesday's attack are thought to have been between the ages of 12 and 16.

Sharif will now be hoping to form a consensus on military operations against the TTP and its allies, which have been ongoing since June 15.

Al Jazeera's Kamal Hyder, reporting from the Army Public School in Peshawar, said Tuesday's attack had been condemned by all of Pakistan's political parties.

"Even Imran Khan's opposition party has said they will set aside their political differences during this meeting.

"Pakistan was already at war, a blowback was expected when the army began its campaign [in northern Waziristan] in June, and that blowback seems to be happening now.

"You must remember that most people will be burying their children," he added.

All seven Taliban fighters were killed during the military operation to retake the school, officials said.

It was one of the bloodiest attacks in Pakistan's history.

Most of the younger pupils escaped, as the older students were deliberately targeted in the attack.

Attack condemned by Taliban

The Afghan Taliban condemned the attack on Tuesday, saying it was against Islam.

"The intentional killing of innocent people, children and women are against the basics of Islam and this criteria has to be considered by every Islamic party and government," Afghan spokesman Zabihullah Mujahid said in a statement.

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The Army Public School had about 1,100 students and teachers present, when the attack started at about 10:30am local time (05:00 GMT), military officials said.

The deadly attack triggered shock and outrage across the world. Pakistani Prime Minister Nawaz Sharif said it was a "national tragedy", calling those killed "my children".

The Pakistani military began Operation Zarb-e-Azb against the TTP and its allies on June 15, and said that it had so far retaken large areas of territory from the group, and killed more than 1,270 of it fighters.

The army is also carrying out a military operation in Khyber Agency, which borders Peshawar, where it says it has killed at least 179 fighters.

Drone strikes

In a separate development, A US drone strike in eastern Afghanistan killed four Pakistani Taliban and seven other fighters, a district official.

Mahlem Mashuq, the governor of Sherzad district in Nangarhar province, said the drone's missiles hit a pickup truck killing all 11 occupants on Tuesday afternoon.

Asad Hashim contributed to this report from Islamabad.

Source: Al Jazeera and agencies