By Nic Robertson, Paul Cruickshank and Jomana Karadsheh reporting from Tripoli, Libya

A senior Libyan official told CNN that the U.S. is flying surveillance missions with drones over suspected jihadist training camps in eastern Libya because of concerns over rising activity by al Qaeda and like-minded groups in the region but said that to the best of his knowledge, they had not been used to fire missiles at militant training camps in the area.

The revelation follows a failed attack on the U.S. Mission in Benghazi on Tuesday night, which a shadowy jihadist group claimed was to avenge the death of al Qaeda No. 2 Abu Yahya al-Libi.

The official said that one militant commander operating in Derna, Abdulbasit Azuz, had complained that a drone strike had targeted his training camp in the east of Libya. Last month, there were reports of explosions outside the Derna area in the vicinity of the camps, according to a different source.

The CIA's covert drone strike program is rarely publicly acknowledged. It has been widely reported that drones have been deployed to target militants in Pakistan, Yemen and Somalia.

The U.S. flew drones for a while after the NATO intervention in Libya to monitor chemical and biological sites, US military officials tell CNN. But the officials would not comment on whether drone flights were ongoing.

The senior Libyan official said it would be bad if such a strike had occurred. He added that the Americans' use of drones in a surveillance capacity had been discussed at the top level of the transitional Libyan government.

As CNN has reported, Azuz is a senior al Qaeda operative and longtime close associate of the group's leader, Ayman al-Zawahiri, who was dispatched to Libya from the tribal areas of Pakistan in spring 2011, according to several sources. There, he subsequently recruited fighters.

Azuz is a veteran jihadist who fought the Soviet-backed government in Afghanistan in the early 1990s, according to several sources. He later to moved to the UK, where he increasingly came on the radar screen of British security services for his radical recruitment efforts in Manchester. In the period after the July 2005 London bombings, he was detained in the Belmarsh high-security prison and placed under a Control order, according to the sources.

He left the UK in 2009 and traveled to the tribal areas of Pakistan, from where al-Zawahiri redeployed him to Libya to set up a bridgehead for the terrorist group, according to the sources.

According to one source, Azuz has dispatched men as far west as Ajdabiya and Brega in his attempt to build up al Qaeda operations in eastern Libya.

According to the senior Libyan official, five radical Islamist militant commanders are operating in the Derna area, with 200 to 300 men under their command in the camps.

According to Libyan security sources, within the militant ranks in Derna, there are 20 to 30 hardcore jihadist fighters who are cause for most concern. One source said a number of Egyptian jihadists are also present in the Derna area, as well as fighters belonging to al Qaeda's North African affiliate, al Qaeda in the Islamic Maghreb.

Recently, Libya's grand mufti, Asadiq Gherayli, met with the five militant commanders, and four of them, including Azuz, agreed with the government terms not to carry out attacks.

Only one refused: Sufian bin Qumu (also known as Abu Faris al Libi), a released Guantanamo detainee who is believed to be operating a camp in the mountainous woods along the sea outside Derna.

Qumu, 53 is a Libyan jihadist who participated in jihad in Afghanistan in the early and mid-1990s and joined the Libyan Islamic Fighting Group in Sudan in the mid-1990s, where he worked as a truck driver for bin Laden's company, according to a detainee assessment compiled while he was at Guantanamo.

He subsequently moved to Pakistan and then to Afghanistan, during which time he left the Libyan Islamic Fighting Group and declared allegiance to the Taliban, according to the assessment. He was arrested in Pakistan after fleeing Afghanistan after the fall of the Taliban and handed over to U.S. authorities.

The assessment described him as having a "long-term association with Islamist extremist Jihad and members of Al-Qaida and other extremist groups."

Moammar Gadhafi's Libyan government said the assessment considered him "a dangerous man with no qualms about committing terrorist acts." The assessment said he had once assaulted guards at the detention facility in Cuba.

It added that before becoming a jihadist, Qumu had served as a tank driver in the Libyan army before spending several years in prison on accusations of murder and drug dealing. It was after his escape in 1993 that he first traveled to Afghanistan.

According to one source, locals in Derna believe he was behind an assassination attempt several months ago on Abdel Hakim al Hasadi, another militant commander in the city.

Several senior Libyan officials said they were aware of Azuz and Qumu's presence in the Derna area.

They say local tribes, including the Obeidi tribe, which control the area are keeping watch on the camps. One source said the tribes have the authority to capture and kill the occupants. "No one who leaves ever goes back," one source said.

Another source said that the militants are proving increasingly unpopular in Derna and that residents recently forced one group to vacate a camp on the outskirts of the city.

The jihadist group that claimed responsibility for the failed attack on the U.S. Mission in leaflets left at the scene called itself the Imprisoned Omar Abdul Rahman Brigades. It promised more attacks against American interests.

It was first heard from late last month, when it claimed responsibility for an attack on a Red Cross office in Benghazi. A purported video of the attack was apparently posted on jihadist websites that regularly feature statements by al Qaeda. The video showed several rockets being fired into a building at night.

In claiming responsibility, the group stated, "We do not recognize (state) borders when we plan for our operations, and we have prepared a message that will soon reach America in response to polluting the clarity of the defiant city of Derna," according to a translation by Flashpoint Partners, which monitors jihadist websites.

According to a source in touch with jihadist militants in eastern Libya, there are indications the group has roots in the Derna area.