Rome, March 21 - Italy is set to return to two anti-piracy marines to India on Friday to stand trial on murder charges after a diplomatic tug-of-war escalated between the two countries. Indian Prime Minister Manmohan Singh on Wednesday said that the refusal to turn over the two men, Massimiliano Latorre and Salvatore Girone, who had been granted leave "casts a shadow" over the two countries' relations. Italy's government said it has asked and obtained from the Indian authorities written guarantees of the treatment and the recognition of the two marines' fundamental rights as recognized by international law. India's justice minister earlier on Thursday said the two men had until tomorrow to return to the Asian nation where they are due to stand trial before escalating the situation further. The two marines had been held in India since February 2012 after a shooting incident in international waters in which two Indian fishermen, Jelestine Valentine and Ajesh Binki, were killed. Italy has always denied that India has jurisdiction over the case, as it took place in international waters. As a sign of goodwill, the two marines were allowed to return to Italy to spend Christmas with their families and - after returning to India as agreed between the two governments - were allowed back to Italy again to vote in February elections, after which they never returned.