The arrests were carried out early on Wednesday morning and targeted several politicians. Among those detained are three mayors in the Istanbul province and two mayors in the Adana province in the country's southern parts.
In total, eleven CHP-affiliated mayors in Turkey have now been arrested on suspicion of alleged corruption. One of these is Ekrem Imamoglu, the mayor of the city of Istanbul, who has been seen as Recep Tayyip Erdogan's perhaps most prominent challenger for the presidency.
In total, around 70 people connected to Istanbul's administration have been detained in various raids during the winter.
The arrest of Imamoglu in March led to widespread protests in the country.
