The White House for the first time will release casualty figures from its controversial drone program, officials said on Monday, amid criticism that the airstrikes often kill civilians instead of the intended terror targets.

Lisa Monaco, President Barack Obama's top homeland security adviser, said the administration will publish a review of its air strikes on terror targets worldwide outside of active war zones, disclosing casualty figures for both fighters and civilians.

The planned report comes after a 2013 pledge by Obama to provide more transparency in its drone program that has become a keystone in America's counterterrorism efforts, amid criticism that the program is too opaque and frequently kills innocent civilians.

"In the coming weeks, the administration will publicly release an assessment of combatant and non-combatant casualties resulting from strikes taken outside areas of active hostilities since 2009," Monaco said in remarks made during a speech at a Washington think tank.

The report will be published annually, she said.

A seemingly ever-expanding global war against extremist groups means the United States relies heavily on drones to monitor hostile lands and launch missiles at suspected extremists in countries such as Pakistan, Somalia and Yemen.

Obama has drastically expanded the drone program during his tenure, but his administration provides scant information on strikes.

Critics say many drone strikes kill civilians, and the aircraft alienate and radicalize local populations on the ground.

Civil rights grounds said the move was welcome but said the administration needs to go even further.

Jameel Jaffer, a senior official with the American Civil Liberties Union, called the planned report "an important step," but said it "should be part of a broader reconsideration of the secrecy surrounding the drone campaign."

He called on the government to release legal memos authorizing the strikes, acknowledge individual strikes and investigate strikes that kill civilians.

"The authority to use lethal force should be subject to more stringent oversight by the public, by Congress, and, at least in some contexts, by the courts," Jaffer said.

US strikes have sometimes killed Westerners, such as in January 2015 when Al-Qaeda hostages American Warren Weinstein and Italian Giovanni Lo Porto were killed in a raid. Obama expressed his "deepest apologies" to their families.

According to the nonpartisan Stimson Center think tank, which last month released a report critical of the drone program, the US has drone bases in more than a dozen countries, including Afghanistan, Djibouti, Ethiopia, Kuwait, Niger, the Philippines, Qatar, Seychelles, Saudi Arabia, Turkey and the UAE.