|Reaper is a drone the size of a jet fighter, piloted remotely from the United States [GALLO/GETTY]
The White House has confirmed that the US military has unmanned drone aircraft in Ethiopia but says no strike missions are being launched from the east African country.
"The US has unarmed and unmanned aircraft at a facility there to be used only for surveillance as part of a broad, sustained, integrated campaign to counter terrorism," Captain John Kirby, a US defence department spokesman, said on Friday. "These unmanned aircraft are being used only for surveillance and not conducting strike missions."
The White House confirmed the drone flights out of an airfield in the city of Arba Minch after the Washington Post newspaper first reported the operation late on Thursday.
The Post, citing unnamed officials, reported that the MQ-9 Reaper drones flying out of Arba Minch were armed, but the US government on Friday denied that they were.
Reapers are roughly the size of jet fighters and can be armed with bombs and missiles. They fly twice as fast and high as the more well-known Predators.
The US presence in Ethiopia is a delicate political issue there, and American officials are anxious to downplay the role of the military and intelligence agencies across the region.
"There are no US military bases in Ethiopia. It's an Ethiopian airfield," Kirby said.
In support of Ethiopia's 2006 invasion of Somalia, US warplanes carried out attacks from a base in Ethiopia. The government ended the arrangement once it became public.
The US also operates Camp Lemonnier, a permanent military base in Djibouti, and an air base in Manda Bay, Kenya, where counter-terrorism experts believe armed drones that have carried out strikes in Somalia are also based.
Unarmed Reapers reportedly also fly from another base in the Seychelles in the Indian Ocean to monitor pirates.
Kenya sent forces into southern Somalia this month to chase fighters from al-Shabab, Somalia's biggest armed anti-government group, but has denied the US or other Western countries are actively involved in the operations.
White House spokesman Jay Carney said the US was determined to press ahead with counterterror efforts, which have increasingly focused on al-Shabab and al-Qaeda's network of offshoots in the Arabian peninsula.
In July, a US drone, possibly flown from Manda Bay, was reported to have killed two senior members of the movement.
"We are harnessing every tool of American power - military, civilian and diplomatic. The United States is strengthening its intelligence, military and security capabilities and drawing from the full range of enforcement tools in co-ordination with partners around the globe," Carney told reporters.
Under President Barack Obama, the US has increasingly relied on drones to carry out covert strikes against al-Qaeda, the Taliban and others in Pakistan, Yemen and Somalia.
The raids are conducted under the authority of the Central Intelligence Agency, not the military, but special operations forces and drone aircraft can be assigned to the spy agency for the strikes.
The covert strikes are an open secret but senior US officials decline to publicly acknowledge the raids.
Administration officials declined to comment on whether the drone surveillance flights out of Ethiopia were focused on Somalia.
But a defence official, who spoke on condition of anonymity, said: "We're obviously very concerned about instability in Somalia."