Two new reports on the use of drones by the United States in its ongoing war against Al-Qaeda add to a growing chorus of concern among human-rights groups that the Obama administration's drone program has violated international law and caused unnecessary civilian deaths, fear and chaos in Pakistan and Yemen.

One report, released by Amnesty International, reviews 45 drone strikes in North Waziristan and surrounding regions in Pakistan in 2012 and 2013. The area is considered a hotbed of Al-Qaeda activity and is the most targeted location in the world for drone strikes. The other report, released by Human Rights Watch, details the circumstances and aftermath of six strikes in Yemen, where drones are used less frequently than in Pakistan.

Both reports conclude that in many cases, drone strikes may have breached international laws. Both also say that the White House's and CIA's lack of transparency surrounding the drone program makes it unaccountable to the citizens of the U.S. as well as to unintended victims of the attacks.

"The biggest problem is the accountability vacuum," Naureen Shah, Amnesty International's advocacy adviser for Pakistan, told Al Jazeera. "(The Obama administration) has created a situation where they're claiming success at killing the right people and ignorance or indifference to the wrong people dying."

The two reports come days after the United Nations released its own report on the U.S. drone program. The U.N. also urged the United States to be more transparent about its program, and the international body plans to present the report to the U.N. General Assembly on Oct. 25.

Amnesty International investigators conducted on-the-ground research into nine of the 45 drone strikes they reviewed. They found that in some cases, innocent civilians were killed in the strikes. In one circumstance, 18 workers were killed by multiple missiles in North Waziristan as they were settling into an evening meal. In another, a 68-year-old grandmother was killed by a Hellfire missile as she harvested vegetables from her family's farm.

"We cannot find any justification for these killings," said Mustafa Qadri, Amnesty International's Pakistan researcher, in a statement. "It is hard to believe that a group of laborers — or an elderly woman surrounded by her grandchildren — were endangering anyone at all, let alone posing an imminent threat to the United States."

These attacks, the organization says, are in violation of international law. Amnesty International said that one attack it investigated may also be a war crime.

On July 6, 2012, a U.S. drone appears to have struck a group of people who arrived to help rescue those injured in an attack a few minutes earlier, according to Amnesty International. If the U.S. intentionally targeted those who were injured or the people assisting previous them, that could be considered a war crime, according to Shah.

But there is no way of knowing what the U.S.'s motivations were, Shah said.

In the vast majority of strikes, the target, any accidental deaths and information about whether a strike was successful are all kept confidential.

That, the groups say, makes it hard to ensure that the program falls within the bounds of international law. It also makes it difficult to determine how many people have been killed by drones.

The Bureau of Investigative Journalism estimates that 407 to 926 civilians have been killed since 2004 in Pakistan, while the Pakistani government says the number is between 400 and 600. The United States says information on civilian deaths is classified.

By not acknowledging civilian deaths or releasing details of the strikes, the U.S. government makes it impossible for families of civilians killed by drones to receive compensation, according to Amnesty International.

The strikes, coupled with the U.S. government's secrecy, create an atmosphere of anxiety in areas where drone attacks are frequent, according to the reports. Many are afraid to speak out against the strikes because they fear that would associate them with terrorists in the eyes of the U.S.

Human Rights Watch's report on Yemen, where the drone program is less prevalent, came to many of the same conclusions that the Amnesty International report did.

Both say the U.S. should work to make the facts and legal justification surrounding drone strikes more transparent and investigate when there are claims of innocent lives lost. Both groups say the international community should condemn the drone program in its current state and push the U.S. and its allies to fall in line with international law.

But it is unclear what, if anything, can be done about the U.S. drone program.

According to the Obama administration and some experts, only so much can be revealed about the program without jeopardizing national security.

"The Obama administration has been rather transparent, but there are limitations," Charles J. Dunlap, a former Air Force major general and now a professor at Duke University, told Al Jazeera. "What they haven't been transparent about is the information about specific cases. That's because adversaries go to school when any information is released."

This isn't the first time the Obama administration's drone program has come under fire.

Responding to mounting pressure, Obama gave a speech in May in which he promised to release more information about the program. But nothing has come of that speech so far.