India's Supreme Court has said Italy's envoy does not have legal immunity, in an escalating row over Rome's refusal to return two marines charged with murdering two Indian fishermen.
India's Chief Justice Altamas Kabir said the court had "lost trust" in Italy's ambassador Daniele Mancini.
The court reiterated last week's order for him not to leave the country.
The marines were allowed to go home to vote in last month's polls on condition that they return to stand trial.
Mr Mancini had given his personal assurance that the two marines - Massimilian Latorre and Salvatore Girone - would return within four weeks as ruled by the court.
There has been no comment from the Italian embassy in Delhi or Ambassador Mancini.
But on Friday, Rome said it was seeking a "friendly agreement" with India to resolve the row.
The office of President Giorgio Napolitano said Italy wanted an agreement based on "international law".
'Mistook for pirates'
In its order on Monday, the three-judge Supreme Court bench said Ambassador Mancini, who had negotiated the marines' release, had waived his immunity by giving an undertaking to a court that the pair would return.
"A person who comes to court and gives an undertaking has no immunity," Chief Justice Kabir said.
The court set 2 April as the next date of hearing and restrained the Italian ambassador from leaving India "until further orders".
The marines are accused of shooting the fishermen in Kerala in February 2012. They said they mistook them for pirates.
Rome says it wants its nationals to be tried in Italy. Italy believes India has no jurisdiction in the case, saying the incident took place in international waters,
India has said that irrespective of the location of the ship, it has the right to try the marines as the fishermen were unarmed Indians on board an Indian fishing boat.
Prime Minister Manmohan Singh warned that "there will be consequences" unless Italy returned the marines.
In unusually strong language, the prime minister said Italy's refusal to do so was "unacceptable".