ISTANBUL — Prosecutors early Sunday requested that detained Istanbul Mayor Ekrem Imamoglu, the top challenger to President Recep Tayyip Erdogan, be formally arrested over allegations of corruption and terror links.

A court is now set to decide whether the popular opposition figure will be charged and jailed pending a trial.

The arrest this week of Imamoglu has intensified political tensions and sparked widespread protests across Turkey, with demonstrators rallying in multiple cities to voice their opposition.

Many view his arrest as a politically driven attempt to remove Imamoglu from the next presidential race, currently scheduled for 2028. Government officials reject the accusation and say Turkey’s courts are independent.

Police questioned Imamoglu for around five hours on Saturday as part of an investigation into allegations of aiding the outlawed Kurdistan Workers’ Party, or PKK, the Cumhuriyet newspaper reported. A day earlier he was questioned for four hours over the corruption accusations. The mayor rejected all charges during both interrogations.

He was later transferred to a courthouse for questioning by prosecutors along with some 90 other people who were also detained with him.

Authorities barred access to the courthouse using barricades on local roads and closing nearby metro stations. Hundreds of police officers and over a dozen water cannon trucks were deployed. Still, hundreds gathered in front of the building shouting: “Rights, law, justice!”

Largest wave of protests in Turkey in more than decade

Others gathered outside the Istanbul city hall or took to the streets to denounce the mayor’s resignation for a fourth night of nationwide protests, in the largest wave of street demonstrations in Turkey in more than a decade.

The demonstrations were largely peaceful but a group of protesters, trying to break through barricades to reach Istanbul’s main square, threw flares, stones and other objects at police, which responded with pepper spray. Some demonstrators said rubber bullets were fired.

Police used water cannons and tear gas to scatter demonstrators in Ankara.

Interior Minister Ali Yerlikaya said 323 people were detained following protests Saturday night. Earlier, he said: “There will be no tolerance for those who seek to violate societal order, threaten the people’s peace and security, and pursue chaos and provocation.”

Growing protests in reaction to the arrest

Imamoglu was detained on Wednesday following a dawn raid on his residence over allegations of financial crimes and links to Kurdish militants. Dozens of other prominent figures, including two district mayors, were also detained.

On Friday, police in Istanbul used pepper spray, tear gas and rubber bullets to push back hundreds of protesters who tried to break through a barricade in front of the city’s historic aqueduct while hurling flares, stones and other objects at officers. Police also dispersed groups that had rallied outside of the city hall for a third night running, after the opposition Republican People’s Party leader, Ozgur Ozel, delivered a speech in support of the mayor.

Simultaneously, police broke up demonstrations in Ankara, the capital, as well as in the Aegean coastal city of Izmir, resorting to forceful measures at times, according to television images. Thousands marched in several other cities calling on the government to resign.

Earlier, Erdogan said the government would not tolerate street protests and accused the opposition party of links to corruption and terror organizations.

The Istanbul governor’s office announced it was expanding a ban on demonstrations until March 26 and imposed restrictions on the entry and exit of vehicles deemed to be transporting people “likely to participate in unlawful activities.”

Erdogan on Saturday accused the CHP’s leadership of turning the party “into an apparatus to absolve a handful of municipal robbers who have become blinded by money.”

He also accused it of “doing everything to disturb the public peace, to polarize the nation.”

Presidential primary to be held

Imamoglu’s arrest came just days before he was expected to be nominated as the opposition Republican People’s Party’s presidential candidate in a primary on Sunday. Ozel has said that the primary, where around 1.5 million delegates can vote, will go ahead as planned.

The opposition party has also urged citizens to participate in a symbolic election on Sunday — through improvised ballot boxes to be set up across Turkey — to show solidarity with Imamoglu.

In a tweet posted shortly before his arrival at the courthouse, Imamoglu urged the public to safeguard the ballot boxes for Sunday’s primary, “Don’t forget: they are very afraid of you and your democratic right to vote.”

In an earlier message, Imamoglu described his arrest as a “coup” and accused the government of exploiting the judiciary and worsening the country’s troubled economy.