The Obama administration is preparing to announce as early as next week that it believes around 100 civilians have died in nearly 500 U.S. drone strikes since 2009, U.S. officials tell NBC News.

That is a far lower estimate than those of the three major independent groups that seek to track the secret operations in the Middle East, South Asia and Africa. The highest estimate among those groups puts civilian casualties from drones at over 1,000.

The disclosure, which is expected to cite an estimated range of civilian deaths lower and higher than 100, represents the latest attempt by the president to fulfill his promises to be more transparent about the controversial secret killing program he ramped up when he took office. Despite those vows, officials continue to release very little information about the targets and circumstances of each lethal strike.

Obama is expected to issue an executive order requiring annual disclosures of civilians killed in counter-terrorism strikes, officials say, a development first reported by the Daily Beast.

Human rights groups praised the move, but remain skeptical about the numbers.

“This is a big victory,” said Naureen Shah, who directs Amnesty International’s human rights program in Washington. However, she added, “It’s impossible to assess their claims without the administration acknowledging or denying the specific cases that we’ve put forward.”

U.S. officials have credited drone strikes carried out by the CIA and the military’s Joint Special Operations Command with putting al Qaeda on its heels. Officials have long said that Hellfire missiles fired from unmanned drones are far more precise than conventional bombing when it comes to targeting terrorists living among civilians.

Read more at NBC