Italy said two marines on trial for murder in India would return to the country by Friday, in a stunning turnaround after Rome earlier unleashed a diplomatic furore by saying they would not go back.

The two, Massimiliano Latorre and Salvatore Girone, had been granted a special leave last month by an Indian court to return to Italy to vote in elections but had skipped bail.

The government said on Thursday 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.

"The marines agreed to this decision," it added.

Prime Minister Mario Monti met with Defence Minister Giampaolo Di Paola and Steffan de Mistura, a junior foreign minister who has taken a lead on the case, to discuss the issue on Thursday.

De Mistura said the decision was a "difficult" one.

Italian President Giorgio Napolitano said he appreciated the "sense of responsibility" displayed by the two marines.

The government had announced on March 11 that the marines would not return from their leave.

The two are accused of shooting dead two Indian fishermen they mistook for pirates off the Indian port of Kochi last year while they were serving as security guards on an Italian oil tanker.

After Italy said the marines would not return, Indian authorities forbade Italy's ambassador to New Delhi, Daniele Mancini, from leaving the country, saying he had broken a written promise.

Sonia Gandhi, the Italian-born head of India's ruling party, had accused Rome of an unacceptable "betrayal", and Prime Minister Manmohan Singh had warned Italy that there would be "consequences".

Italy had accused India of violating international laws on diplomatic immunity as the Indian Supreme Court issued a decision requiring Mancini to seek the court's permission to leave the country.

European Union foreign policy chief Catherine Ashton on Tuesday defended Mancini, saying diplomatic immunity "should be respected at all times" and warning that limiting his movement "would be contrary" to international obligations.