WASHINGTON (AP) — The U.S. government's covert program using unmanned drones to strike at terrorists inside Pakistan is not likely to stop or change, despite new criticism from a U.N. human rights expert.

U.S. officials insist the CIA program has been an effective tool to take out insurgents along the Afghanistan-Pakistan border, particularly those hidden beyond the reach of the military. The stepped-up use of drones over the past year has shown no signs of slowing down and was credited earlier this week with the killing inside Pakistan of al-Qaida's third in command.

The Obama administration does not acknowledge the secret program, but one senior U.S. official defended its use Wednesday, saying a careful and rigorous targeting process is used to avoid civilian casualties. The official, who is familiar with the operation, spoke on condition of anonymity because the program is classified.

The program, which officials say has killed hundreds of insurgents in dozens of strikes over the past year, has been condemned by critics who say it may constitute illegal assassinations and violate international law. They argue that intelligence officers conducting the strikes could be at risk of prosecution for murder in foreign countries.

In a 29-page report released Wednesday, Philip Alston, the independent U.N. investigator on extrajudicial killings, called on countries to lay out rules and safeguards for carrying out the strikes, publish figures on civilian casualties and prove they have attempted to capture or incapacitate suspects without killing them.

"Unlike a state's armed forces, its intelligence agents do not generally operate within a framework which places appropriate emphasis upon ensuring compliance with international humanitarian law, rendering violations more likely and causing a higher risk of prosecution both for war crimes and for violations of the laws of the state in which any killing occurs," wrote Alston, a New York University professor.

The report to the U.N. Human Rights Council puts unwanted scrutiny on the intelligence operations of the United States, Israel and Russia, who Alston says are all credibly reported to have used drones to kill alleged terrorists and insurgents.

He said the drone strikes by intelligence agencies launched in Afghanistan, Pakistan and elsewhere are particularly fraught because of the secrecy surrounding them.

Other experts disagree.

"Drone operations are essential," said Bruce Riedel, a former CIA officer and a senior fellow at the Brookings Institution Saban Center. "The drones are part of a much broader effort to put pressure on al-Qaida through the war in Afghanistan. They're the cutting edge of the pressure, but they're not the only pressure."

Earlier this week, al-Qaida leaders confirmed that a drone strike in Pakistan had killed the terror group's No. 3 officer and top commander in Afghanistan, Mustafa al-Yazid.

U.S. authorities routinely refuse to talk openly or release data about the program, but as criticism has heightened they have slowly begun to respond quietly to the complaints.

"Without discussing or confirming any specific action or program, this agency's operations unfold within a framework of law and close government oversight," said CIA spokesman George Little. "The accountability's real, and it would be wrong for anyone to suggest otherwise."

Administration officials have pointed to a carefully worded speech in March by State Department legal adviser Harold Koh, who said that "U.S. targeting practices, including lethal operations conducted with the use of unmanned aerial vehicles, comply with all applicable law, including the laws of war." The Obama administration, he said, is committed to following the law in its operations against terrorists.

The senior U.S. official said Thursday that the drones use precision targeting, and that civilian casualties have been overstated.

In describing the decision-making process, the official said the strikes are launched only when a vetted target comes into clear view, and that — much like the military — intelligence officers take into account the principles of necessity, the need for a carefully weighed response and the obligation to minimize innocent civilian casualties.

The U.S. official cited Pakistan, where he said there was no evidence to prove large numbers of innocent lives have been lost due to drone strikes.

This view has been challenged by human rights groups and independent observers, who say remotely operated drones risk ingraining a video game mentality about war and can never be as accurate as eyewitness confirmation of targets from the ground.

"The point is that innocent people have been killed, this has been proved over and over again," said Louise Doswald-Beck, a professor of international law at the Geneva Graduate Institute in Switzerland.

"If you don't have enough personnel on the ground, the chances of your having false information is actually quite huge," she told The Associated Press.

Among the most sensitive recommendations in Alston's report is that governments should disclose "the measures in place to provide prompt, thorough, effective, independent and public investigations of alleged violations of law." Doing so would almost certainly blow open the lid on all manner of secret counterterror operations.

The report also warns that CIA personnel could be extradited to those countries where the targeted killing takes place and wouldn't have the same immunity from prosecution as regular soldiers.

Alston claims more than 40 countries now have drone technology, with several seeking to equip them with lethal weapons.

Doswald-Beck said the next step could be the development of fully autonomous drones and battlefield robots programed to identify and kill enemy fighters — but without human controllers to ensure targets are legitimate.

"If that's the case you've got a major problem," she said.



Alston report: http://bit.ly/TargetKillReport


Jordans reported from Geneva. Associated Press Writer Nahal Toosi in Islamabad and Matthew Lee in Washington contributed to this report.

(This version CORRECTS the day the report was released to Wednesday.)