New Delhi, Mar 13 (IANS): Gujarat Chief Minister Narendra Modi Wednesday said the central government should explain their "action plan" for the return of Italian marines facing trial for killing two Indian fishermen last year.

"The UPA (United Progressive Alliance) should explain to the nation what action it plans to take to ensure the return of the Italian marines to face trial in India," Modi said in a post on the microblogging website Twitter.

"On the issue of Italian marines, nothing short of their return to India must be the acceptable outcome," he tweeted.

The two Italian marines Massimiliano Latorre and Salvatore Girone, members of a military security team protecting a cargo ship from pirate attacks, are accused of shooting the fishermen off the Kerala coast February last year, sparking a diplomatic row between New Delhi and Rome.

The Italian marines said they mistook the fishermen for pirates.

The Supreme Court in February allowed Latorre and Girone to fly to Italy to vote in the Feb 24-25 national election.

The apex court was given an undertaking that the marines would return in four weeks to face legal proceedings in India. But the Italian embassy Monday informed New Delhi that the marines would not return to India.

The government has assured that all efforts would be made to bring the Italian sailors back.