Sanaa, Yemen (CNN) -- U.S. airstrikes targeted militant hideouts and arms caches in separate attacks over three days in Yemen, killing at least 64 suspected al Qaeda insurgents before the strikes ended Sunday, senior Yemeni officials told CNN.
Officials at U.S. Central Command and the Defense Department contacted Sunday provided no information on the purported attacks.
U.S. officials rarely discuss the drone program, though privately they have said covert strikes using drones are legal and an effective tactic in the fight against extremists.
The latest strike involved at least five U.S. drones and took place in the Jabal Khanfar region of Jaar, located in southern Abyan province, two senior Yemeni security officials said. At least six suspected al Qaeda militants were killed, Yemeni officials said.
A member of the military committee -- Yemen's highest security authority -- confirmed that strike, and said the Yemeni government was given no advance warning of it.
"The United States did not inform us on the attacks. We only knew about this after the U.S. attacked," the committee member told CNN.
The strike was the third such attack on suspected al Qaeda targets in less than three days, according to Yemeni officials.
The United States was also involved in two other major attacks on Friday and Saturday, which killed at least 58 suspected al Qaeda insurgents, two senior Yemeni defense ministry officials said.
The Friday airstrikes occurred in the Yemen province of al-Baitha in areas used as launching pads for militant attacks. The second attack took place in the towns of Jaar and Zinjibar in Abyan province.
One of the ministry officials said the attacks happened late in the day, when Yemeni air forces are not capable and trained to conduct such operations.
Earlier, separate security officials had said Yemeni air forces were behind the first two airstrikes.
At least 34 suspected al-Qaeda militants, among them four senior leaders in the network, were killed in the al-Baitha attack, said Mohammed al-Ameri, governor of the province.
Smoke from the air raids covered the skies hours after the strike. Security forces also formed new checkpoints in nearby districts.
Residents said military aircraft roam the skies of the province around the clock.
Yemeni rights organizations condemned the alleged U.S. airstrikes, calling them illegal. HOOD, a prominent Sanaa-based rights organization, said that no one has the right to kill another person without first bringing that person to trial.
"This is illegal and dozens were killed without given a chance to prove their case. We are against any U.S. attack in Yemen," said Mohammed Nagi Allow, HOOD's president.
More than 200 Yemeni troops were killed recently in clashes against al Qaeda in Abyan.
Militants took over a military camp there, seizing large caches of weapons. They are still holding 72 troops hostage.
Yemen has been desperately trying to weaken terror militant groups after they succeeded in taking over large parts of Abyan province last year.
The United States has been backing Yemeni efforts against al Qaeda and has periodically struck targets inside Yemen, as occurred in September, when a drone strike killed American-born cleric Anwar al-Awlaki.