Police on Sunday detained two members of the Italian navy accused of killing two Indian fisherman they mistook for pirates off the coast of Kerala, officials said.

The Italians, members of a navy security team, were on an Italian merchant vessel when the incident happened on Wednesday. Since last October their regiment has supplied specialist anti-pirate personnel to accompany cargo ships that request help.

The two accused have been taken to Kochi where they will be interrogated by police, a police officer, who did not wish to be identified, told Reuters.

The Ministry of External Affairs said Italian Foreign Minister Giulio Terzi Di Santagata had called his Indian counterpart S.M. Krishna on Saturday to discuss finding a mutually acceptable procedure to establish the facts beyond any doubt and determine responsibilities.

The fishermen were unarmed, and the law should be allowed to take its course, a statement said.

The external affairs minister conveyed to the Italian foreign minister that it was unfortunate that innocent lives had been lost which could have been avoided had the naval personnel on board Enrica Lexie been careful and exercised restraint, the statement said.

Italy's ambassador to India was last week summoned to a meeting with an official at the Foreign Office to explain what had happened. The ambassador was asked to ensure the crew of the ship co-operate with the authorities.

A team of Italian diplomats are expected to arrive in New Delhi on Sunday to discuss the matter with Indian authorities, local media reported citing sources.