The Italian Foreign Minister quit after his government returned two marines to India to face trial for killing two fishermen.
“I can no longer be part of this government and I announce my resignation,” Giulio Terzi told the lower house of parliament. “My reservations about sending the marines back to India were not listened to.”
The marines, Salvatore Girone and Massimiliano Latorre, were on anti-piracy duty on an Italian commercial tanker in February last year when they allegedly murdered the two fishermen off the coast of Kerala.
They said they fired warning shots at a boat they believed to be a pirate vessel.
Since the incident, India and Italy have been embroiled in an escalating row at a time when Rome is trying to secure a major deal to sell helicopters to the Indian government.
Latorre and Girone were sent back to Delhi on Friday in what defence forces chief Admiral Luigi Binelli Mantelli called a “farce”.
Terzi said he resigned to protect the “honour of the country, of the armed forces and Italian diplomacy”, drawing loud applause from MPs.
But the Defence Minister, Giampaolo Di Paola, refused to do likewise, saying: “I won’t abandon a ship in difficulty, with Massimiliano and Salvatore on board, until the last day of the war.”
Prime Minister Monti responded to the resignation with surprise.
He said he had met Terzi earlier on Tuesday and the foreign minister had not mentioned his intention to quit.