Pakistan said on Friday that its top security and foreign affairs adviser has conveyed deep concerns to the United States over a recent drone attack that killed at least six students and teachers of a religious school in the country's northwest. The U.S. spy aircraft fired missiles on the "madrassa" in Hangu district of Khyber Pakhtunkhwa province Thursday morning. That was the first U.S. drone attack in settled area which raised concerns in Pakistan as the U.S. has expanded its covert drone campaign outside the tribal regions. "The adviser to the prime minister for national security and foreign affairs conveyed the deep concerns of the government of Pakistan to the U.S. on the 21 November drone strike," the foreign ministry said Friday. "The deep concerns of the government of Pakistan were conveyed to the U.S. ambassador in Islamabad on the same day," a foreign ministry statement said. The U.S. ambassador was told that the November 21 drone attack was therefore a matter of particular concern to Pakistan that the strike targeted a location in the Khyber Pakhtunkhwa province and also resulted in the unfortunate killings of several persons including children. The ministry added the ambassador was told that this has deeply disturbed the people of Pakistan. The adviser re-emphasized that the drone strikes are not only a violation of Pakistan's sovereignty and territorial integrity, these are also having a negative impact on the government's efforts to pursue the consensus achieved in the All Parties Conference to explore the dialogue process in order to bring peace and stability in Pakistan and the region. "The government of Pakistan would demand immediate cessation of these drone strikes," the statement said. It said the present government has been raising its concern over the drone strikes with the U.S. Administration and at the United Nations. The prime minister during his recent visit to the U.S. had also raised the issue with President Obama and other senior U.S. leaders. Security sources say that targeted seminary was linked to the Afghanistan's Haqqani Network and Maulvi Ahmed Jan, deputy of the group's chief was among those killed in the strike. The U.S. carried out the strike a day after adviser to the prime minister on foreign affairs Sartaj Aziz, told a Senate Foreign Affairs committee that Washington has promised not to launch attacks during Pakistani government talks with the Taliban. Aziz said the U.S. drone strike which killed the Taliban chief, Hakimullah Mehsud, this month, has harmed the government peace talks with the militants. Mehsud was killed when American spy aircraft rained missiles into North Waziristan tribal region on November 1, just a day before a team of top Islamic scholars were to meet him to discuss about the agenda and venue for the negotiations. Tehrik-e-Taliban Pakistan refused to talk to the government after the killing of their chief and also announced revenge attacks. Ruling coalition in Pakistan's Khyber Pakhtunkhwa province Friday announced to block supply route for NATO forces from November 23 as a protest against the drone strikes. The issue of drone strikes is a source of tension between Pakistan and the U.S. as Washington is in no mood to change its covert operation despite Islamabad's public condemnation. The U.S. insists Pakistan has failed to act against the al- Qaeda operatives and Taliban militants in Waziristan tribal region who are accused of cross-border attacks into Afghanistan.