The Central Investigation Agency-operated spy plane fired three missiles at the Islami Madrassa Muktaba Darul Uloom at Thall in Hangu district of Khyber-Pakhtunkhwa province. Thall is located within the settled areas and just outside North Waziristan Agency.
According to Afghan Taliban sources, those killed included Ahmad Jan, a close aide of Haqqani network chief Sirajuddin Haqqani, and commanders Gul Marjan and Hamidullah. Five others were injured.
The attack came a day after Sartaj Aziz, the Prime Minister Nawaz Sharif’s adviser on foreign affairs and national security, told a parliamentary panel that the US has assured Pakistan it will not conduct drone strikes during the government's talks with the militants.
Thursday's strike was also the first since the one that killed Tehrik-e-Taliban Pakistan chief Hakimullah Mehsud on November 1. Senior leaders, including Interior Minister Chaudhry Nisar Ali Khan, had accused the US of attempting to "sabotage" talks with the Taliban by targeting Mehsud.
Pakistan Tehrik-e-Insaf, an opposition party led by former cricketer Imran Khan, described the drone attack as a "declaration of war" by the US.
The party, which will hold a sit-in on Saturday to block North Atlantic Treaty Organisation supply trucks going though Khyber-Pakhtunkhwa province which it rules, said the time had come for Pakistan to take tough action.
"This was a declaration of war against the people of Pakistan by the US," party spokesperson Shireen Mazari said. She demanded to know whether the government and military were sleeping while "Pakistan was being attacked or were they complicit".
Analysts said the latest strike could increase tensions between Pakistan and the US.
Aziz told the senate standing committee on foreign affairs on Wednesday that the US had been informed that the drone strike against Mehsud had disrupted negotiations with the Taliban. He said Washington had given an assurance it would not target militants holding talks.
Aziz did not say how it would be determined that Taliban were holding talks or how Pakistan will update the US about the status of negotiations.
The Haqqani network, based in North Waziristan Agency, has been blamed for devastating attacks on the US and foreign forces in Afghanistan. Despite frequent calls from the US for a crackdown on the group, Pakistan has refused to act.
The group's main financier, Nasiruddin Haqqani, was shot dead in Islamabad on November 11.
Pakistan's foreign office strongly condemned Thursday's drone strike, saying such attacks were a violation of the country's sovereignty and territorial integrity. "There is an across the board consensus in Pakistan that these drone strikes must end," it said in a statement.
Pakistan has been raising its concerns over drone strikes with the US administration and at the United Nations. Sharif, during his recent visit to the US, had raised the issue with US President Barack Obama and other senior leaders. "It has been consistently maintained that drone strikes are counter-productive, entail loss of innocent civilian lives and have human rights and humanitarian implications. Such strikes also set dangerous precedents in the inter-state relations," the statement said.
The strikes have a "negative impact" on the government’s efforts to bring peace and stability in Pakistan and the region, it said.
Image: Residents stand at the site of a drone attack on an Islamic seminary in Hangu district, bordering North Waziristan
Photograph: Syed Shah/Reuters
Whether Pak likes it or not, US drone strikes will go on
'Pak Taliban chief Mehsud killed in drone strike'
Al Qaeda nerds in Pakistan working on drone killers
Is the US' killing-by-drone campaign useful?
Let us do the dirty job, US drones can watch: Pak offers