In a blow to Italy's attempt to internationalise the case of two Italian marines being tried in India for killing two fishermen, UN Secretary-General Ban Ki-moon has asked Rome to resolve the issue bilaterally.

"It's better for the question to be addressed bilaterally, rather than with the involvement of the UN," Ban was quoted as saying by Italian news agency ANSA, sparking fury in Italy.

His comments came a day after Italy petitioned the UN over the trial of the marines under a strict anti-piracy law and vowed to exercise "all options" to bring back its personnel.

Foreign Minister Emma Bonino told Italian parliament that she felt "great bitterness and perplexity" that Ban said the case was a "bilateral" issue. She, however, added that Ban "guaranteed me comprehension and assured he would subsequently take action with the Indian authorities" over the case.

Marines Massimiliano Latorre and Salvatore Girone shot dead two fishermen off the Kerala coast in February 2012, sparking diplomatic tensions between India and Italy.