New Delhi (CNN) -- A diplomatic showdown between Italy and India is escalating, with Rome saying that an Indian court order forbidding the Italian ambassador from leaving the South Asian country breaches international law.
The dispute centers on Italy's refusal to send back two of its marines who are due to face trial in India over accusations they killed two Indian fishermen off the country's coast last year.
Last month, the Indian Supreme Court allowed the two Italian sailors -- Massimiliano Latorre and Salvatore Girone -- to go back to Italy to participate in national elections after Ambassador Daniele Mancini gave assurances they would return in four weeks.
When the two sailors failed to come back last week, the court temporarily barred Mancini from leaving India and demanded an explanation from him.
On Monday, the court extended the travel ban until April 2. And Chief Justice Altamas Kabir suggested that by making a pledge before the court, Mancini had no immunity in the case, according to CNN affiliate IBN.
The Italian foreign ministry responded strongly to the court's actions.
"The decision by the Supreme Court to block our ambassador from leaving the country without the court's permission constitutes an evident violation of the Vienna Convention on Diplomatic Relations, which codifies universally recognized principals," the ministry said Monday.
Article 31 of the convention states that a diplomat enjoys immunity from the criminal, civil and administrative jurisdictions of the receiving state, except in certain cases related to private property, succession and unofficial professional and commercial activities.
India said last week that the court order restricting Mancini's movements didn't contravene the convention.
Italy insists the February 2012 shooting involving its marines happened in international waters and was therefore outside of Indian jurisdiction. Latorre and Girone say they mistook the fishermen for pirates.
Rome said last week that the two sailors wouldn't go back to India, calling the situation "an international dispute between the two states."
In its statement Monday, the Italian foreign ministry said it believes the case of the two sailors should be resolved under international law.
The case has fueled anger 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 last week.
CNN's Harmeet Shah Singh reported from New Delhi, and Jethro Mullen reported and wrote from Hong Kong.