Turkey arrests dozens over online posts after Erdogan rival detained

Authorities in Turkey have arrested dozens of people for "provocative" social media posts, after detaining the mayor of Istanbul Ekrem Imamoglu on Wednesday.

Imamoglu was one of more than 100 people held on charges including corruption and aiding terrorist groups - a move that has sparked protests in Istanbul and the capital Ankara.

A member of the secular Republican People's Party (CHP), Imamoglu is a key rival of President President Recep Tayyip Erdogan and was set to be named as a presidential candidate for the 2028 elections later this week.

Critics call his arrest as "a coup" and are planning further demonstrations, despite Istanbul's pro-Erdogan governor imposing a four-day protest ban.

Interior minister Ali Yerlikaya announced on Thursday morning that police had identified 261 "suspect account managers" online.

They allegedly posted content which broke laws on "inciting the public to hatred and hostility" and "incitement to commit a crime".

"Thirty-seven suspects were caught and efforts are continuing to catch the other suspects," he said, adding that more than 18.6 million posts appeared online about Wednesday's arrests by 0600 local time (0300 GMT) on Thursday.

But these efforts so far have not deterred demonstrators.

Imamoglu may have spent his first night in detention but the municipality is still controlled by his opposition party - for now.

As commuters boarded trains at metro stations across the city, a recording of one of Imamoglu's previous public speeches blared out from loudspeakers: "I promise you with my honour that I am going to win this fight."

There were calls for demonstrations at six universities in Istanbul on Thursday. Students who have only ever known the rule of Erdogan marched on the streets in the pouring rain chanting, "We are not scared, we won't be silenced, we will not obey" - a common opposition slogan in Turkey.

However, numbers of protesters are still relatively small for a city with more than 16 million people. For now, they are unlikely to raise political pressure on Erdogan to release Imamoglu.

The office of the detained mayor has called for protesters to gather for a second night in a row outside the municipal hall.

CHP leader Ozgur Ozel addressed supporters at one rally on Wednesday night and called on them to "fill the streets". A party spokesman told AFP news agency Ozel is expected to address crowds outside the municipal hall again on Thursday at 2030 local time (1730 GMT).

Police clashed with demonstrators in several places, firing tear gas and pepper spray.

Turkish authorities have also restricted social media usage nationwide after Wednesday's arrests, including the use of WhatsApp, according to UK-based internet watchdog Netblocks.

Dozens of police officers were involved in the raid on Imamoglu's house in Istanbul early on Wednesday morning.

He was one of 106 people detained in the operation.

The arrests come as part of a major nationwide crackdown in recent months, targeting opposition politicians, municipalities, journalists and figures in the entertainment industry.

Some fear more opposition figures will be brought in for questioning over the coming weeks as part of a campaign of intimidation.

Last month when two senior business leaders from TUSİAD, the Turkish Industry and Business Association, denounced the recent crackdown on the opposition, they were called in for questioning and may face up to five years in prison.

Local prosecutors also announced on Thursday they had seized a construction company owned by the Istanbul mayor, as part of a investigation into alleged financial crimes.

Opposition figures say the arrests are politically motivated. But the justice ministry on Wednesday criticised those who linked Erdogan to the arrests, and insisted on their judicial independence.

Last year, Imamoglu won a second term as Istanbul's mayor, when his CHP party swept local elections there and in Ankara.

It was the first time since President Erdogan came to power that his party was defeated across the country at the ballot box.

The elections were also a personal blow to the president, who grew up in and became mayor of Istanbul on his rise to power.

Erdogan has held office for the past 22 years, as both prime minister and president of Turkey. Due to term limits, he cannot run for office again in 2028, unless he changes the constitution.

The CHP's presidential candidate selection, in which Imamoglu is the only person running, is set to take place on Sunday.

Around 1.5 million party members will vote in the internal election.

CHP leader Ozel has said they will vote for Imamoglu regardless of where he is.

The party has also called on citizens to vote in a symbolic election, with plans to place ballot boxes in districts all over Turkey for members of the public to show their support for the detained mayor.