Lisa Monaco, President Barack Obama's Homeland Security advisor, said figures would be released in the "coming weeks" of people killed in drone strikes since 2009, including both fighters and 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. She added that the report would then be published annually.

"We know that not only is greater transparency the right thing to do, it is the best way to maintain the legitimacy of our counter-terrorism effort and the broad support of our allies," Monaco said.

The figures would, however, not cover strikes in "areas of active hostilities," such as Iraq, Syria and Afghanistan, where hostilities against the US remain, she told the Council on Foreign Relations.

Monaco portrayed the move as part of President Obama's efforts to make US operations more transparent. The US has faced criticism from human rights groups for the use of drones causing civilian deaths instead of hitting intended terror targets in strikes in Pakistan, Afghanistan, Yemen, Somalia, Libya and beyond.

Soldiers out, drones in

The Stimson Center think tank released a report in February critical of the drone program, which is conducted by both the Defense Department and the CIA, saying that 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 United Arab Emirates.

The United States relies heavily on drones to monitor hostile terrain, and for launching missiles at suspected extremists abroad. President Obama has drastically expanded the drone program during his tenure, but his administration has thus far only provided limited information on strikes.

Human rights groups have accused the Obama administration of not being open enough about the precise guidelines that govern drone strikes, with claims of "collateral damage" being commonplace.

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

ss/jm (AFP, AP, dpa, Reuters)