Two Italian marines accused of killing two Indian fishermen will be sent back to India by Friday, the Italian government has said, reversing its previous decision not to send them back to face trial.

Massimiliano Latorre and Salvatore Girone were granted special leave to return to Italy last month by an Indian court, but skipped bail, elevating diplomatic tensions between the two countries.

The Italian government said on Thursday that that it had received "ample assurances" from Indian authorities "on the treatment that the marines will receive and the defence of their fundamental rights".

"The government decided, also in the interests of the marines, to maintain the commitment taken when they were granted leave to take part in the elections, to return to India by March 22," it said, adding that the marines had agreed to the decision.

Italy's foreign ministry sparked fury in India earlier in March when they said that the two marines would not return to India.

As a result, India's Supreme Court ordered the Italian ambassador not to leave the country, escalating the stand-off and spurring Catherine Ashton, the European Union foreign policy chief, to warn that New Delhi was violating international law.

The two men are accused of killing two Indian fishermen, who they say they mistook for pirates, off the southern Indian port of Kochi in February 2012, while they were serving as security guards on an Italian oil tanker.

Girone and Latorre have maintained that they only fired warning shots.

Italy has insisted the shooting happened in international waters during an international anti-piracy mission and that Rome should have jurisdiction.