ROME: An Italian military prosecutor on Wednesday questioned two marines who last month failed to return to India to face charges of killing two Indian fishermen while on anti-piracy duty in 2012.

The marine's failure to return triggered outrage in India and escalated into a diplomatic standoff last week when India's top court barred the Italian ambassador from leaving the country.

Dressed in uniform, marines Salvatore Girone and Massimiliano Latorre were accompanied by lawyers to the hearing with prosecutor Marco De Paolis, who has opened an investigation into the two for disobeying orders, ANSA news agency reported, without going into further details.

The military charges may be transferred to Rome's regular criminal court where the two are under investigation for murder, ANSA said, citing the prosecutor. De Paolis did not respond to a call to his office.

India's Supreme Court ruled in January that India had jurisdiction to try the marines. But Italy has challenged that decision, arguing that the shooting took place in international waters and that the two should face any trial at home.

Wednesday's questioning “marks the beginning of the Italian jurisdiction over the case involving the two marines”, a government source told Reuters.

The marines, part of a military security team protecting the tanker Enrica Lexie from piracy, are accused of shooting two fishermen to death in February 2012 in waters of the southern Indian state of Kerala.

Girone and Latorre have said they fired warning shots only.

They were detained in India to face trial, but the Supreme Court allowed them to go home for four weeks to vote in a parliamentary election on Feb. 24-25, provided they returned to India.

But earlier this month, Italy advised the Indian government the two would not return.