"(If the punishment is approved, it will be) an attack on Italy," chairman of the lower house foreign affairs committee Fabrizio Cicchitto was quoted as saying by ANSA news agency today.
He recently met the marines - Massimiliano Latorre and Salvatore Girone, currently lodged at the Italian Embassy in New Delhi.
The two marines were deployed on the Italian-flagged oil tanker MT Enrica Lexie when they shot dead two Indian fishermen off Kerala coast in February, 2012, sparking diplomatic tensions between India and Italy.
India's National Investigation Agency (NIA) has sought sanction to prosecute the two marines under the 'Suppression of Unlawful Acts Against Safety of Maritime Navigation and Fixed Platforms on Continental Shelf' Act (SUA), a provision which has only death penalty as punishment.
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India has, however, given an assurance to Italy that the two would not be awarded death penalty.
The NIA today told a special court in New Delhi it was "ready" with a chargesheet against the marines and would file it after the Supreme Court decides on the issue raised by the Italian government.
Rome wants the marines to be tried in Italy, claiming the incident took place in international waters. However, India said it has the right to try the Italian personnel as the victims were Indians on board an Indian fishing boat.