A court in the Turkish capital, Ankara, ordered on Thursday the arrest of at least four people and the release of seven others out of eleven recently held over alleged illegal wiretapping as part of "parallel state" operations.
All those held were from the country's Telecommunications Directorate, or TIB.
On Wednesday, police took 26 suspects into custody in the operation; warrants were issued for 11 of them.
Operations started after it was confirmed that encrypted phones belonging to senior Turkish leaders had been wiretapped.
Those affected include President Recep Tayyip Erdoğan, Prime Minister Ahmet Davutoğlu, Turkey's Supreme Court head Haşim Kılıç, the chief of General Staff Necdet Özel and Deputy Prime Ministers Bülent Arınç and Ali Babacan.
Phones belonging to other senior figures such as Interior Minister Efkan Ala, Energy Minister Taner Yıldız, head of the country's National Intelligence Organization (MİT) Hakan Fidan plus members of the National Security Council are also thought to have been wiretapped.
In total, 363 incidents of illegal wiretapping of the aforementioned names have been confirmed, most of which were carried out between December 17-25, 2013, when an anti-graft probe targeted a number of high-profile figures, including the sons of three former government ministers and leading Turkish businessmen.
The government has denounced the probe as a "dirty plot" constructed by the Gülen Movement which allegedly infiltrated the country's institutions, including the judiciary and the police, to undermine the Turkish state.