ISTANBUL, May 18 (Xinhua) -- Turkish police on Monday detained 57 suspects, including several high-ranking municipal officials, in one of the largest single-day sweeps targeting a subsidiary of the Istanbul Metropolitan Municipality (IBB), local authorities announced.

The Istanbul Chief Public Prosecutor's Office said that anti-fraud police units had conducted coordinated raids across six provinces, including Istanbul, Adana, Bursa, Diyarbakir, Konya and Yalova.

Of the 58 suspects targeted, 57 were apprehended, while efforts are underway to capture the remaining fugitive, the statement said.

The investigation focuses on Bogazici Facility Management Services, an IBB subsidiary. Prosecutors allege that the firm systematically manipulated multiple public tenders organized by it, in violation of procurement regulations.

Among the high-profile figures detained is Sema Akca, the general manager of the subsidiary, along with numerous other top executives and procurement officials. The suspects have been transferred to the police headquarters for interrogation.

The probe is part of a sweeping investigation into the municipal structures linked to Ekrem Imamoglu, the elected mayor of Istanbul, who was suspended from office and placed in pre-trial detention in March 2025.

Imamoglu is currently on trial alongside over 400 co-defendants, facing up to 2,430 years in prison if convicted on more than 140 charges, including establishing a criminal network, laundering criminal proceeds, and corruption. ■