Imamoglu, the primary political opponent of President Tayyip Erdogan and his polling leader, was imprisoned in March while awaiting trial on corruption accusations. He is also accused of providing support to a terrorist organization.
His arrest led to the worst protests in a decade, economic instability, and allegations of a politicized judiciary, all of which the mayor has rejected. The government denies those allegations and asserts the independence of the courts.
Of the 52 people who were arrested over the weekend as part of the inquiry, 34 were freed with judicial limitations, according to broadcaster NTV.
As part of a crackdown on the main opposition that started late last year, Turkish media claimed on Saturday that police had arrested scores of Istanbul municipality employees as part of legal investigations centered on Imamoglu.
