ISTANBUL — The leader of Turkey’s main opposition on Friday renewed a call on supporters to take to the streets for peaceful demonstrations against the arrest of Istanbul’s mayor and top rival to President Recep Tayyip Erdogan, even as authorities widened a ban on protests and criticized the call as irresponsible.

Mayor Ekrem Imamoglu was arrested in a dawn raid on his residence on Wednesday over alleged corruption and terror links, escalating a crackdown on opposition figures and dissenting voices. Several other prominent figures, including two district mayors, were also detained.

Many view the arrest as a politically driven attempt to remove a popular opposition figure and key challenger to Erdogan from the next presidential race, currently scheduled for 2028. Government officials reject claims that legal actions against opposition figures are politically motivated and insist that the courts operate independently.

Since Imamoglu’s arrest, thousands of people have gathered at Istanbul’s city hall for night-time rallies, and clashes have erupted between demonstrators and police in Istanbul, the capital, Ankara, and Turkey’s third largest city, Izmir.

The most violent clash took place at Ankara’s Middle East Technical University, where police deployed tear gas and water cannons to disperse the demonstration and students claimed rubber bullets were used. The government has denied the use of the bullets.

On Friday, authorities in Ankara and Izmir announced a five-day prohibition on demonstrations, following a similar ban imposed earlier by the Istanbul governor’s office. The bans came after the country’s justice minister acknowledged people’s right to demonstrate but said street protests amid ongoing judicial investigations were unacceptable.

Still, Ozgur Ozel, the chairman of the Republican People’s Party, CHP, made a fresh appeal for people to gather and demonstrate.

“I invite tens of thousands, hundreds of thousands, and millions to peacefully demonstrate, express our democratic reaction, and exercise our constitutional rights,” he said.

Ozel said: “To those who say that calling people to the streets is irresponsible, I say this: We are not the ones filling these streets and squares. It is your lawlessness and injustices that have brought people out.”

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 the primary, where some 1.5 million delegates can vote, will go ahead as planned.

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

It was not clear when authorities would begin questioning the mayor, who can be detained without charges for up to four days. Analysts say Imamoglu could be removed from office and replaced by a “trustee mayor” if he is formally charged with links to the outlawed Kurdistan Workers’ Party, which is listed as a terrorist organization by Turkey and its Western allies.