That assurance came after Italy changed its earlier decision and agreed to send Massimiliano Latorre and Salvatore Girone back to India to face trial in the shootings of two Indian fishermen.
India's CNN-IBN television channel, quoting sources, said the two marines would be taken to the Italian Embassy in New Delhi after their arrival and would be available to face trial. The sources also were quoted as saying there was a possibility the two could serve any prison term in Italy.
Italy's decision to let them return appeared to soften what had been a worsening diplomatic situation.
Indian External Affairs Minister Salman Khurshid told Parliament Italy had been assured Latorre and Girone would not face the death penalty.
He said Italy had expressed concern about the death penalty.
The minister said the cases of the marines "would not fall in the category of matters which attract the death penalty, that is to say the rarest of rare cases. Therefore, there need not be any apprehension in this regard."
Earlier, the Italian government said it had agreed to send back Latorre and Girone after receiving written guarantees from Indian authorities about their treatment and the recognition of their fundamental rights under international law, Italy's ANSA news agency reported.
The case against the two relates to the shootings of the Indian fishermen off the coast of India's southern state of Kerala in February 2012. Italy has said the incident occurred in international waters where the two marines had been guarding their Italian tanker and the Indian fishermen were mistaken for pirates.
The marines, who were later granted bail, were allowed to return to Italy by the Indian Supreme Court so they could vote in Italy's election in February. with the assurance from Italian Ambassador to India Daniele Mancini that they would return to India this month to stand trial.
The Italian government later declined to send them back, questioning India's jurisdiction in the case and suggesting their trial be held in Rome, setting off a diplomatic standoff.
Indian Prime Minister Manmohan Singh had been quoted as saying Italy's earlier refusal to send the two accused men back to India "casts a shadow" over relations between the countries. Italy had been denying India had jurisdiction over the case.
When the two marines failed to return, the Indian Supreme Court temporarily restrained the Italian ambassador from leaving the country despite Italy's insistence about the ambassador's diplomatic immunity.
Khurshid said the Supreme Court had ruled that a special court would be set up to try and dispose of the marines' case.