Turkey's top judicial board has ruled on Tuesday that the investigation into the two Gülenist judges, who were suspended after they decided to release 76 Gülenist suspects (called the "members of the parallel state" in Turkey) that allegedly tried to topple the government, should continue.

The Supreme Board of Judges and Prosecutors, or the HSYK, decided on Tuesday that Metin Özçelik, judge of the Istanbul 29nd Penal Court of First Instance and Mustafa Başer, judge of the Istanbul 32nd Penal Court of First Instance, should continue to be investigated after they were suspended a day earlier.

Özçelik and Başer were suspended on grounds of "damaging the reputation and influence of the judiciary" after they attempted on Saturday to order the release of Hidayet Karaca, the chairman of the Samanyolu Media Group, and 75 others, including some police chiefs, being probed in a "parallel state" case.

Istanbul judge Erdoğan Şimşek also declared on Tuesday that the "unauthorized" release decisions were "null and void", confirming a similar declaration by Istanbul's 10th Penal Court of Peace on Sunday.

The ongoing "parallel state" case was launched on December 14 2014, against senior media figures and police officers in 13 provinces across Turkey for allegedly being affiliated with what the government describes as a "parallel state" - refered to as the so-called "Gülen movement", a purported group of bureaucrats embedded in the country's institutions, including the judiciary and the police which the Turkish government alleges are plotting to undermine it.

Members of the "parallel state" - which allegedly involves U.S.-based preacher Fethullah Gülen and his supporters - are also accused of orchestrating a corruption probe which targeted high-ranking Turkish officials in December 2013.

Turkey's President Recep Tayyip Erdoğan and Prime Minister Ahmet Davutoğlu both slammed the judges' order for the suspects in the "parallel state" case to be freed, claiming that the decision "came from Pennsylvania", referring to the place where Fethullah Gülen lives.

Karaca has been charged with "managing a terrorist organization".