Congo-Brazzaville's jailed opposition leader Jean-Marie Mokoko has returned to the country a month after he was taken for treatment in Turkey's capital, Ankara.

Mokoko was serving a 20-year jail term when he became sick and was flown to Ankara.

His lawyer Yvon Eric Ibouanga told AFP news agency he was allowed to see the politician after he returned to the country and that he was in "good shape".

The lawyer said they were working on a request for him to be freed.

Mokoko was charged with undermining state security and illegal possession of weapons and ammunition and imprisoned in 2019.

The former chief of staff of the armed forces finished third in the 2016 presidential elections. Denis Sassou Nguesso was controversially declared winner.