Rights groups Saturday condemned Pakistan's decision to hang two convicted militants in its first executions for six years, as leaders vowed decisive action in the wake of a Taliban school massacre that left 149 people dead.

Pakistan described the bloody rampage in the northwestern city of Peshawar on Tuesday as its own "mini 9/11", saying it was a game changer in its fight against terror.

Prime Minister Nawaz Sharif relinquished the six-year ban on the death penalty in terror-related cases two days after the school attack, with two militants convicted of separate terrorism offences the first to face the noose.

The Human Rights Watch termed the executions "a craven politicized reaction to the Peshawar killings", demanding that no further hangings be carried out.

"Pakistan’s government has chosen to indulge in vengeful blood-lust instead of finding and prosecuting those responsible for the horrific Peshawar attack," the group said in a statement Saturday.

The two militants hanged Friday in central Punjab province were Aqil, who was convicted for an attack on the army headquarters in Rawalpindi in 2009, and Arshad Mehmood who was convicted for his involvement in a 2003 assassination attempt on former military ruler General Pervez Musharraf.

Around 1,000 people turned up for their burial in the town of Kahuta, around 18 miles southeast of Islamabad, according to an AFP photographer at the scene.

Meanwhile, Pakistan put all its airports on red alert Saturday as the military intensified its operations against militants in the country's lawless tribal areas.

The army was deployed to guard major prisons housing militants and a number of educational institutions, including the esteemed Quaid-e-Azam University in Islamabad, were shut indefinitely citing security threats.

Officials have said there would be up to ten more executions in the coming days.

Rights campaign group Amnesty International estimates that Pakistan has more than 8,000 prisoners on death row, with more than 500 of them convicted on terror-related charges, according to the government.

"This is a cynical reaction from the government. It masks a failure to deal with the core issue highlighted by the Peshawar attack, namely the lack of effective protection for civilians in north-west Pakistan," Amnesty said about Friday's executions.


'Final elimination'

The United Nations also called for Pakistan to reconsider executing terror suspects, saying that "the death penalty has no measurable deterrent effect on levels of insurgent and terrorist violence" and "may even be counter-productive".

The army has been waging a major offensive against longstanding Taliban and other militant strongholds in the restive tribal areas on the Afghan border for the last six months.

But a series of fresh strikes after the Peshawar attack, which wrought devastation at an army-run school, suggest the military is stepping up its campaign.

Seven militants were killed on Saturday morning in two separate incidents as security forces hit their hideouts in the restive northwest.

A US drone strike in the lawless tribal area also hit a militant compound killing five militants early Saturday.

As the Peshawar tragedy unfolded, army chief General Raheel Sharif said the attack had renewed the forces' determination to push for the militants' "final elimination".

The atrocity was already the deadliest terror attack in Pakistan's troubled history, surpassing the 139 killed in bomb blasts targeting former prime minister Benazir Bhutto in 2007.

But the head of the hardline Islamabad Red Mosque slammed the army operation in North Waziristan as "un-Islamic" and said the TTP slaughter in Peshawar was understandable.

"O rulers, O people in power, if you will commit such acts, there will be a reaction," Maulana Abdul Aziz told worshippers in his Friday sermon.

Around 250 people protested outside the Red Mosque in Friday evening, denouncing hardliners like Abdul Aziz as Taliban sympathisers.

Later, the Islamabad police registered a case against the cleric for threatening the protestors after they staged a sit-in protest outside a local police station demanding a case against the cleric.