First Class Judicial Magistrate A K Gopakumar, before whom the marines' moved their plea, said it was not within the purview of his court to consider the bail application of the accused charged under IPC section 302 (murder).
The marines, Latore Massimiliano and Salvatore Girone, were brought from the Central Prison in Thiruvananthapuram and produced before Goapakumar on expiry of the remand period.
After the magistrate extended the remand of the marines, their counsel, a senior advocate of the Supreme Court, moved their bail application.
The naval guards were arrested on February 19 and charged with murder of fishermen Valentine Jalastine and Ajesh Binki, who took to sea from Neendakara in Kollam, on February 15.
The accused were in police custody for the first 14 days and had been lodged in a special cell in the central prison in Thiruvananthapuram since March 5 after the court remanded them to judicial custody.