The interrogation of Istanbul Mayor Ekrem Imamoglu began on the third day of his detention, Turkiye Today reported.

According to the television, Imamoglu was summoned for questioning on the 56th hour of his detention.

According to the website of the Cumhuriyet newspaper, the mayor of Istanbul, who is in temporary detention, has begun testifying before the public prosecutor, who will decide whether to refer him to court and whether he will be kept in custody.

It is recalled that the mayor of Istanbul was detained on the morning of March 19, as part of two separate investigations launched by the city's General Prosecutor's Office on charges of "corruption" and "terrorism-related acts."

Incriminating audio recording

Separately, according to information revealed today, the Istanbul Public Prosecutor's Office has included an audio recording in the corruption investigation it is conducting in the Istanbul Metropolitan Municipality (IBB).

The recording allegedly reveals the illegal acquisition of data on Istanbul residents and includes a conversation between Murat Ongun, a senior advisor to Mayor Imamoglu, and Serdal Taskin, former CEO of IBB's Culture Inc.

The investigation is targeting Imamoglu and around 100 other suspects on charges of criminal organization, bribery, embezzlement, manipulation of tenders and illegal acquisition of personal data.

The leaked footage shows Ongun using his company, Reklam Istanbul, to obtain the personal data of Istanbul residents through a data management platform (DMP).

In this conversation, Taskin allegedly warns Ongun about the dangers of accessing such data:

"You could make three, four, maybe five or six times more money through DMP, but that would create a huge problem. It would show that we have access to data for the entire city. This is a huge issue for us."

Ongun reportedly responded: “Having personal data from Istanbul may not bring me direct financial gain. I may not use it or share it, but I could use it internally. Not for financial gain, but in another way – it’s still an investment. I don’t see the DMP just as a tool for selling products – I wanted it for both reasons.”

Taskin then expresses concerns about regulatory oversight, citing a previous case where the bank faced potential fines of 50 to 60 million euros for similar violations.

In Turkey, large protests have been taking place in the last 24 hours, and people have reacted en masse to the arrest of Ekrem Imamoglu, who is Recep Tayyip Erdogan's main opponent in the national elections.

The mayor of Istanbul has been highly critical of the Turkish president, as his arrest has sparked protests across the country by citizens of all ages. It all began on Wednesday (19/3) when authorities handcuffed Imamoglu and stripped him of his university degree, which is necessary for him to be eligible to lead a party as president.

VIDEO | Incidents and arrests at protests in Turkey in support of Imamoglu