Hundreds of thousands of protesters demonstrated against the arrest of Istanbul's opposition mayor, Ekrem Imamoglu, defying President Recep Tayyip Erdogan's warning that Turkey will not allow "street terrorism" late Friday.

Demonstrators marched for the third night in a row over Imamoglu's detention, Turkey's largest street rally in more than a decade.

Turkey's opposition leader Ozgur Ozel revealed that over 300,000 people participated in large rallies around Istanbul on Friday in response to the arrest of the city's mayor, Ekrem Imamoglu.

"We are 300,000 people," the CHP leader addressed the massive throngs in front of City Hall, explaining that protesters had assembled at various locations around Turkey's largest city owing to road and bridge restrictions that prevented everyone from congregating in one area.

🟡 HAPPENING NOW: Scenes show the massive scale of ongoing protests across Turkey, now entering their third consecutive day.

Demonstrations continue to spread nationwide, as police respond with tear gas, water cannons, and pepper spray in multiple cities. pic.twitter.com/0tpG8tpJvG

— red. (@redstreamnet) March 21, 2025

Imamoglu, Istanbul's influential mayor and top political challenger to President Recep Tayyip Erdogan, was arrested for fraud and terror charges, prompting his party, the CHP, to call for new rallies in Turkey's largest city.

He shouted that Erdogan was attempting to "twist the arm" of Imamoglu by weaponizing the judiciary. 

As he spoke, violence broke out on the margins of the rally, with riot police firing tear gas and rubber bullets, according to two AFP journalists who were both shot in the leg.

Protesters in Ankara Turkey, mainly students, are pushing back police and their water cannons. pic.twitter.com/pahzX0K1uB

— kakasloi (@kakasloi) March 21, 2025

Outside Istanbul City Hall, police deployed pepper spray and rubber bullets, according to AFP, while riot police in Izmir used water cannons and tear gas to disperse protesters, according to the opposition Halk TV.

"I don't believe in the allegations about Imamoglu. There is no man as honest as him," said Necla, a 56-year-old, to AFP. 

Protests expanded fast from Istanbul to at least 40 of Turkey's 81 regions, according to an AFP assessment.

As CHP's Ozel called for nationwide protests, Erdogan vowed Turkey would not surrender to "street terror", accusing Ozel of "grave irresponsibility" and raising concerns about potential legal action. Authorities extended the protest ban to Ankara and Izmir, closing key routes, while police clashed with demonstrators in Istanbul and Ankara, arresting 88.

Interior Minister Ali Yerlikaya says 16 police officers were injured. Police detained 54 people for what police called "incitement to hatred" in internet remarks.

The decision against Imamoglu has caused a significant blow to the Turkish currency, and the BIST 100 stock exchange was trading lower on Friday, down over eight percent shortly before 1400 GMT.

Despite Imamoglu's imprisonment, the CHP has pledged to hold its primary on Sunday, where it would formally nominate him as its candidate for the 2028 election.

The party stated that it would let anybody, not only party members, to vote, stating, "Come to the ballot box and say 'no' to the coup attempt!"

According to observers, the government may strive to obstruct the primary in order to prevent Imamgolu from receiving further support.

"If a large number of people show up and vote for Imamoglu, it will further legitimize him domestically and really move things in a direction that Erdogan doesn't want," Gonul Tol of the Middle East Institute in Washington told AFP.