Turkey's President Recep Tayyip Erdogan on Friday filed a lawsuit against Istanbul's powerful opposition mayor for allegedly slanderous remarks at a protest rally the day earlier, Turkish media reported.
The lawsuit accuses Ekrem Imamoglu of making "unfounded accusations including slander and violated Erdogan's rights" in a way that damaged his reputation and incited hatred, the state-run Anadolu news agency said.
The case centres on remarks that Imamoglu, a key figure in the main opposition Republican People's Party (CHP), made at a demonstration against the arrest of another opposition mayor for alleged links to the banned Kurdish PKK militant group.
It was not immediately clear which of his remarks had prompted the lawsuit but court documents cited by Anadolou said Imamoglu "acted with the aim of humiliating the president in front of the public".
Imamoglu, who was elected as Istanbul mayor in 2019, is often portrayed as Erdogan's biggest political rival and is widely expected to run in the 2028 presidential race.
He is seen as one of Turkey's most popular politicians.
Two years ago, Imamoglu was sued for defamation after describing Istanbul election officials as "idiots" during the 2019 Istanbul mayoral election.
A court found him guilty, sentenced him to nearly three years in jail and barred him from politics for the duration of the sentence, prompting an international outcry.
Imamoglu has appealed while continuing to serve as mayor.
At the time, Erdogan insisted the case had nothing to do with him.
The 70-year-old Turkish leader launched his own political career in the 1990s by being elected as mayor of Istanbul.