A Turkish court on Sunday jailed Istanbul Mayor Ekrem Imamoglu, President Tayyip Erdogan’s main political rival, pending trial on corruption charges, in a move likely to inflame the country’s biggest protests in more than a decade.

The decision to send Imamoglu to jail comes after the main opposition party, European leaders and tens of thousands of protesters criticized the actions against him as politicized and undemocratic.

As the courtroom developments unfolded, there were signs that the mayor’s troubles were galvanizing opposition against Erdogan’s government, which has run Turkey for 22 years.

Thousands of Republican People’s Party (CHP) members and non-members streamed into polling stations nationwide to elect Imamoglu its candidate in a future presidential vote.

Shortly after the court ruling, the mayor vowed to ultimately defeat Erdogan, and said those who ran the investigation would be held accountable.

“Imamoglu has become Erdogan’s … nightmare,” Mehmet Karatas, an opposition supporter, said outside the courthouse. “We will make Ekrem Imamoglu president.”

Imamoglu’s detention has roiled markets, with the Turkish lira, stocks and bonds suffering heavy declines since Wednesday. Analysts expect more selling pressure after the jailing.

Turkish central bank governor Fatih Karahan met board members of Turkey’s Banks Association (TBB) on Sunday.

Police officers use pepper spray on demonstrators during a protest on the day Istanbul Mayor Ekrem Imamoglu was jailed as part of a corruption investigation, in Istanbul, Turkey, March 23, 2025. REUTERS/Alexandros Avramidis (REUTERS/Alexandros Avramidis)

The central bank will use all instruments within market rules effectively and decisively to maintain stability, Karahan told bankers, the TBB said.

Civil disobedience has been dramatically curbed in Turkey since nationwide Gezi Park protests against Erdogan’s government in 2013, which prompted a violent state crackdown.

Yet thousands gathered again Saturday night outside the Istanbul municipality building and the main courthouse. Hundreds of police used tear gas and pepper spray to disperse protesters, as the crowd hurled firecrackers and other objects.

Though most demonstrations have been peaceful, protesters also clashed with police in the western coastal province of Izmir and the capital Ankara for a third night in a row, with police firing water cannon.

Authorities have detained more than 300 people during protests.

Additional reporting by Huseyin Hayatsever, Mert Ozkan and Mehmet Emin Caliskan; Writing by Jonathan Spicer; Editing by Daniel Wallis, William Mallard, David Goodman, Alison Williams and Giles Elgood