An Ethiopian-born American citizen has pleaded guilty to passing highly classified intelligence to Ethiopia, including information he hoped would help target and kill fighters during the country's 2020 civil war.

Abraham Teklu Lemma, a former US contractor, admitted sharing dozens of classified documents and photographs with senior Ethiopian officials over more than two years, the US Department of Justice said.

"In doing so, he betrayed his oath, his colleagues, and his country, while jeopardizing our national security," said US Attorney Jeanine Ferris Pirro.

The 54-year-old faces up to 22 years in prison under a plea agreement, with sentencing scheduled for next April.

Abraham had worked as a contractor at the State Department, Justice Department and National Reconnaissance Office, the agency responsible for US intelligence satellites.

Prosecutors said Abraham worked with senior figures in Ethiopia's political, military and intelligence establishments between 2021 and his arrest in August 2023.

He secretly removed classified material from secure government facilities, sometimes copying sensitive information into handwritten notes that he carried out of the buildings. He used his position as an IT administrator to extract electronic intelligence files.

"Much of the highly classified information Lemma shared with the Ethiopian government concerned an armed conflict in Ethiopia," prosecutors said.

The information included satellite imagery and details of military activities, which he passed to Ethiopian officials through encrypted messages.

The FBI said Ethiopian officials subsequently used intelligence supplied by Abraham in military operations.

Prosecutors said he hoped the information would help Ethiopia's military identify and kill paramilitary fighters.

"Lemma betrayed the United States to an extraordinary degree," said John Eisenberg, the US assistant attorney general for national security.

In one message to an Ethiopian official in December 2021, he wrote: "We have to finish these people once and for all, otherwise there will never be peace in Ethiopia," court papers showed.

Later that day, he shared further intelligence and urged the official: "Please send Dro[nes]."

The revelations shed light on how sensitive American intelligence was passed to Ethiopian authorities during a devastating civil war that killed hundreds of thousands of people and displaced millions.

He was arrested in Maryland in August 2023 following an investigation into his handling of classified intelligence.

At the time, prosecutors alleged that had removed security markings from intelligence reports and shared information with a foreign intelligence official.

In one exchange, the official asked him to continue providing assistance, to which Lemma replied: "Roger that!"

Pirro, the US attorney, said Abraham had abused his access to some of America's most sensitive intelligence.

She accused him of betraying his colleagues and country with prosecutors saying he "will be prosecuted to the fullest extent of the law".

Abraham pleaded guilty to conspiring to transmit national defence information to a foreign government.

His sentencing is scheduled for 14 April 2027.

The two-year conflict, which began in November 2020, pitted Ethiopian federal forces and their allies against fighters from the northern Tigray region.

It was marked by widespread allegations of atrocities, including massacres, sexual violence and attacks on civilians.

A peace agreement signed in November 2022 ended the main fighting, although tensions and insecurity have persisted.