Turkish authorities on Friday detained dozens of suspects, including the mayors of two opposition-run municipalities, as part of separate investigations into alleged bribery, corruption and abuse of office.

In Istanbul, prosecutors ordered the detention of 41 suspects, including Adalar Mayor Ali Ercan Akpolat, following an investigation into allegations that municipal officials accepted bribes in exchange for issuing permits to unauthorized businesses and construction projects in protected historical areas.

The Anadolu Chief Public Prosecutor’s Office said the investigation focused on claims that officials in the Adalar district, a protected natural and archaeological site off Istanbul’s coast, allowed extensive renovations and construction activities to proceed under the guise of “minor repairs” in return for bribes.

According to prosecutors, complaints and witness statements prompted an inquiry into alleged offenses including bribery, extortion, forgery of official documents, abuse of office and violations of cultural heritage protection laws.

Investigators examined financial records, phone data and witness testimonies and concluded that some business owners and property developers were allegedly allowed to operate without proper licenses or continue unauthorized construction activities after reaching illicit agreements with municipal officials.