New Delhi (CNN) -- India's supreme court has temporarily barred the Italian ambassador from leaving the country as a diplomatic row over Rome's refusal to return two of its marines accused of killing two Indian fishermen intensified.
Last month, the court allowed the two Italian sailors -- Massimiliano Latorre and Salvatore Girone -- to participate in their country's elections after Ambassador Daniele Mancini's assurance about their return in four weeks.
Latorre and Girone are facing trial in India in connection with the 2012 killing of the fishermen off the country's coast. The defendants say they mistook the fishermen for pirates.
On Thursday, the top Indian court demanded an explanation from Mancini by March 18 over his country's decision not to send them back.
"Till then (March 18), Mr. Daniele Mancini shall not leave India without the permission of this court," the order said.
Italy insists the February 2012 shooting involving its marines happened in international waters and was therefore outside of Indian jurisdiction.
In a statement Monday, the Italian Foreign Ministry said the sailors would not go back to India.
"Italy takes this opportunity to inform the Indian government that, given the formal acknowledgment of an international dispute between the two states, Massimiliano Latorre and Salvatore Girone will not be returning to India upon expiration of the leave granted (to) them," it said.
The Italian move has invited strong reaction in New Delhi, with Prime Minister Manmohan Singh warning Rome of consequences.
"Our government has already made it clear that these actions of the government of Italy are not acceptable. They violate every rule of diplomatic discourse and call into question solemn commitments given by accredited representatives of a sovereign government to our supreme court," he said in parliament Wednesday.
"Our government has therefore insisted that the Italian authorities respect the undertakings they have given to the honorable supreme court and return the two accused persons to stand trial in India. If they do not keep their word, there will be consequences for our relations with Italy," he added.
Indian external affairs spokesman Syed Akbaruddin said at a news briefing Thursday that the court action against the Italian ambassador did not violate the global Vienna convention on diplomatic relations. "As of today, I have again said, we do not see any impact on the Vienna convention," he said.