ADDIS ABABA (Reuters) - Ethiopia has filed terrorism charges against a prominent media mogul and opposition politician from the Oromo ethnic group, Jawar Mohammed, the attorney general's office said on Saturday.

Jawar, founder of the Oromiya Media Network and a member of the Oromo Federalist Congress party, was arrested in June amid the widespread unrest that followed the assassination of popular Oromo musician Haacaaluu Hundeessaa.

Jawar and 22 other activists, including Oromo opposition leader Bekele Garba, face charges relating to the violation of anti-terrorism laws, telecom fraud laws and firearms laws, the attorney general's office said in a statement on social media.

Those charged include journalists and scholars. Bekele is a senior leader of the Oromo Federalist Congress.

They will appear in court on Monday to answer to the charges, the attorney general's office said in the statement.

Jawar, a former ally of Prime Minister Abiy Ahmed, was instrumental in the Oromo protests that brought Abiy to power in 2018. But he became a critic of Abiy, accusing the prime minister of failing to protect Oromo interests.

Tuuli Baayyis, Jawar's lawyer, told Reuters that they had learnt about the charges from social media as formal charge papers had not been provided to them yet. He did not comment on the charges.

At least nine people have died in the Oromiya region around Addis Ababa following clashes between Ethiopian security forces and protesters demanding the release of the detained Oromo opposition politicians.

The unrest in Oromiya highlights the challenges facing Abiy ahead of elections which were due this August, but were postponed due to the coronavirus crisis.