ISTANBUL — Jailed Istanbul Mayor Ekrem Imamoglu was brought to the city’s main court on Sunday for questioning as part of a newly launched investigation into possible espionage charges.

Hundreds of his supporters gathered outside in a show of support for the opposition politician seen as a rival of President Recep Tayyip Erdogan.

The espionage investigation, launched two days ago, focuses on alleged links between Imamoglu’s political campaign and a man arrested in July on charges of conducting intelligence activities on behalf of foreign states. Imamoglu’s former campaign manager Necati Ozkan and journalist Merdan Yanardag also face questioning as part of the investigation.

Remanded in custody since March on corruption charges which he denies, this was Imamoglu’s first time out of Istanbul’s Marmara Prison, on the outskirts of Istanbul, in seven months.

Critics see Imamoglu’s arrest, along with those of other mayors from the main opposition party, the Republican People’s Party, or CHP, as part of a broader crackdown on the opposition, which made significant gains in local elections last year. Several CHP-run municipalities have faced waves of arrests throughout the year.

Hundreds of supporters gathered outside the court to show solidarity. CHP Chairman Ozgur Ozel addressed the crowd and said: “As long as these interrogations continue, as long as this cruelty continues, as long as this oppression continues, we will fight democratically, without harming anyone and without allowing anyone to trample on our dignity.”

Faruk Kılıç, a 26-year-old electrician, told The Associated Press that he joined the demonstration to protest what he called injustices against Imamoglu.

“I believe these injustices will never stop, so I will offer my support until the end,” he said.

Imamoglu’s arrest in March sparked protests across the country. Erdogan’s government insists that Türkiye’s judiciary is independent and that investigations focus strictly on corruption.