The marine, 47-year-old Massimiliano Latorre, "was treated excellently in India, but it is clear that he needs rest, peace, and his family," Federica Mogherini said on the eve of the Supreme Court hearing to consider the marine's case.
"We hope that India's Supreme Court will listen to the medical arguments," Mogherini said.
She said, the Italian government fully supports the initiative of the defence lawyers, who have submitted an application to allow Latorre to return to Italy.
Latorre was hospitalised with a condition similar to a mild stroke and was discharged today from a hospital in New Delhi.
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The sick marine had been responding well to treatment after he lost consciousness due to a mild cerebral ischemia, or restriction of blood supply.
Latorre and Salvatore Girone have been held in India since allegedly shooting to death fishermen Valentine and Ajesh Binki during an anti-piracy mission in February, 2012 off the Kerala coast, an incident that sparked diplomatic tensions between India and Italy.
India has removed the possibility of a death penalty but insisted that the marines would still be prosecuted under the anti-piracy law. Now, they face up to 10 years in jail.
Rome wants the marines to be tried in Italy, claiming the incident took place in international waters. However, New Delhi says it has the right to try the Italians as the victims were Indians on board an Indian fishing boat.
Italy has said it may also seek international arbitration in the case.