The Istanbul Chief Public Prosecutor's Office has called in journalist Ugur Dundar, artist and director Mahsun Kirmizigul, singer and actor Gulben Ergen, actress Elcin Sangu and rock musician Hayko Cepkin to give statements as part of the probe.
The summons came as police carried out a fourth wave of operations on Wednesday morning, detaining 13 suspects.
The operation was coordinated by the Istanbul Chief Public Prosecutor's Office and carried out by the Istanbul Provincial Police Department.
Justice Minister Akin Gurlek said the operation examined housing and container purchases, suspicious property transfers, checks issued by the association, and its wider financial and commercial relationships.
Three earlier waves of operations had already been carried out in the investigation. With the latest detentions, the number of suspects under arrest in the case has risen to 28, including Ahbap founder Haluk Levent.
Broadcasters Fatih Portakal and Ece Uner, lawyer Feyza Altun, musician Gokhan Ozoguz and presenter Oyku Serter were called in for statements earlier in the case.
The investigation, launched in July over allegations concerning the use of donations collected after the Feb. 6, 2023 earthquakes, has since widened to examine the financial dealings of Ahbap's executives and individuals and companies linked to them.
The allegations remain part of an ongoing investigation, and authorities have not issued a final court ruling on the merits of the case.