The marines -- Latorre Massimilliano and Salvatore Girone - had contended that they had not committed any offence as alleged by police and that there was no justification in continuing their custody. Earlier, their bail plea was rejected by a lower court in Kollam.
The Union government was impleaded in the case after Justice MK Balakrishnan of the Kerala High Court on May 22 directed the petitioners to implead the Centre.
The naval guards were arrested on Feb 19 and charged with murder of fishermen Valentine Jalastine and Ajesh Binki, who put out to sea from Neendakara in Kollam.
The marines, lodged in central prison, Thiruvananthapuram since March 5, have been shifted to Borstal school, which houses juvenile delinquents, in Kochi.