Five mayors of the main opposition Republican People's Party (CHP) were detained on Wednesday within the scope of the corruption investigation against CHP municipalities, including the Istanbul Metropolitan Municipality (IBB).
The latest arrests included a former lawmaker and three CHP mayors in Istanbul, and two more in the southern province of Adana, a party spokesperson told Agence France-Presse (AFP).
The latest round of arrests brings the total number of jailed CHP mayors to nine in Istanbul province, he said, which includes the city's mayor, Ekrem Imamoğlu.
With two arrests in Adana, that raises the total to 11 CHP mayors.
The latest investigation began at the weekend when a court issued arrest orders for 47 municipal officials in connection with four separate corruption investigations centred on Istanbul, local media reported.
The March 19 arrest and jailing of Imamoğlu sparked big street protests.
Police had already detained nearly 70 people in subsequent raids linked to alleged corruption at Istanbul City Hall, including Imamoğlu's private secretary and his private protection officer.
The CHP has nominated Imamoğlu as its candidate in presidential elections due in 2028 but whether he can run in the elections depends on the fate of numerous trials and probes.