ROME (Reuters) - A U.N. court has ruled that India must allow an Italian marine detained in Delhi for more than four years to go home, Italy’s Foreign Ministry said on Monday.

Salvatore Girone (C) and Latorre Massimiliano (3rd R), members of the navy security team of Napoli registered Italian merchant vessel Enrica Lexie, are escorted as they leave a courtroom at Kollam in Kerala March 5, 2012. REUTERS/Sivaram V/Files

India acknowledged the ruling but said Salvatore Girone would remain under the authority of its Supreme Court which might impose various conditions on his release.

Girone is one of two Italian marines were arrested in India in 2012 on suspicion of killing two fishermen while on an anti-piracy mission on an Italian oil tanker. One returned to Italy with health problems, but India has refused to let Girone go.

He is living in the Italian embassy in Delhi.

“This really is a significant step forward which we have worked on with great dedication,” Prime Minister Matteo Renzi told reporters. “I’ll take advantage of this moment to send a message of friendship to the great people of India.”

The case has soured relations between India and Italy, and also overshadowed Delhi’s efforts to improve its ties with the European Union as other EU countries backed Rome in the row.

Looking to overcome the legal impasse, the two countries agreed last year to move their dispute to the Permanent Court of Arbitration in The Hague and abide by its decision.

The Italian Foreign Ministry said in a statement that in an initial ruling, the court had decided that Girone should be allowed home while it continued its deliberations, which might take many months. The court itself declined to comment.

Responding hours later, India said Girone should be free to return home for the duration of the U.N. investigation, but stressed that he would remain on bail and would have to return to India if the Hague court ruled that India could try the case.

The Ministry of External Affairs said the Supreme Court might demand that he surrender his passport to the Italian authorities and not leave Italy without Indian permission.

The U.N. court will continue to review the merits of the case and no date has been set for a definitive ruling.

“The government underlines that today’s court decision ... will not influence the progress of the arbitration procedures, which should decide if Italy or India has jurisdiction in the case,” Italy’s Foreign Ministry said.

Italy has argued that the case should not be heard in India because it said the incident had occurred in international waters. India said it remained confident that the issue of jurisdiction would be decided in its favour.

Marines are viewed by Italy as state officials immune to foreign prosecution. Italy has paid $190,000 in compensation to each victim’s family.