WASHINGTON/NEW YORK: The United States has officially admitted that it carries out drone strikes in Pakistan's tribal areas with President Barack Obama defending the use of unmanned aircraft in eliminating al Qaeda militants.

After the US president's candid confirmation, the Amnesty International on Tuesday asked the United States to disclose details of the legal and factual basis for use of drones in Pakistan.

President Obama made the rare public acknowledgment on Monday during an hour-long online video chat with users of the social network Google+.

In a statement, the Amnesty International also called for the US to monitor civilian casualties inflicted by drone attacks in Pakistan.

“The US authorities must give a detailed explanation of how these strikes are lawful and what is being done to monitor civilian casualties and ensure proper accountability, said Sam Zarifi Amnesty International's Asia-Pacific Director.

“What are the rules of engagement? What proper legal justification exists for these attacks? While the President's confirmation of the use of drones in Pakistan is a welcome first step towards transparency, these and other questions need to be answered.”

In his remarks, President Obama said on Monday that the drone strikes, which are carried out by the CIA rather than the military, were a “targeted focused effort at the people who are on a list of active terrorists”.

Obama said that the strikes targeted “al Qaeda suspects who are up in very tough terrain along the border between Afghanistan and Pakistan.”

The Amnesty said because of the security situation and difficulty in accessing the terrain it has been impossible for organizations like Amnesty International to verify the number of civilian casualties caused by the drones.

In Islamabad, the Foreign Ministry termed the drone attacks as counterproductive and a violation of Pakistan's sovereignty.

“Drone attacks are unlawful, counterproductive and hence unacceptable. We cannot condone violation of our sovereignty,” Spokesman Abdul Basit said, according to the international media reports.

Responding to the questions in a “virtual interview” that was conducted via Google+ and YouTube, President Obama defended the use of unmanned aircraft to kill Al Qaeda operatives and other militants in Pakistan's tribal areas, thus officially acknowledging the classified CIA drone program.

Over the years, US officials have refused to discuss the issue in public.

“I think that we have to be judicious in how we use drones,” Obama said.

The drones, he said, have been used for “very precise, precision strikes against Al Qaeda and their affiliates.”

Obama went on to say that “obviously a lot of these strikes have been in FATA,” (Federally Administered Tribal Areas) and have been used for “going after Al Qaeda suspects who are in very tough terrain along the border between Afghanistan and Pakistan.”

“This thing is kept on a very tight leash,” Obama said.

The US does not use drones “willy nilly” but in a way that avoids more intrusive military actions, he said.

According to The Los Angeles Times, Obama echoed the arguments of Pentagon and CIA officials, who often make the point in private discussions that the drones can perform targeted strikes and thereby substantially reduce the potential for civilian casualties associated with high-altitude bombing.

But Obama went well beyond that as he took issue with a Monday story in the New York Times, which reported that the State Department is operating a small fleet of surveillance drones to protect US embassies, consulates and personnel stationed in Iraq following the withdrawal of American troops.

Some Iraqi officials are angry about the program and see it as a violation of their sovereignty, according to the Times report.

But Obama said the US still respects the sovereignty of other nations even as it uses drones within their borders.

“The truth of the matter is, we're not engaging in a bunch of drone attacks inside of Iraq,” Obama said.

“There's some surveillance to make sure that our embassy compound is protected.”