Monti, who has been pressing for transfer of the marines to Italy, is believed to have conveyed concern over the conditions in which the two are in, sources said today.
The telephonic conversation took place a few days back, prior to the hearing in Kollam court yesterday which rejected the bail plea of the marines Massimiliano Lattore and Salvatore Girone, the sources said.
The marines were arrested on February 19, four days after they allegedly opened fire while travelling by ship Enrica Lexie and killed two fishermen off the coast of Kerala, apparently suspecting them to be pirates.
The telephonic call from Monti was followed up with Italian Foreign Ministry summoning Indian Ambassador Debabrata Saha in Rome to convey concerns over the murder charges being framed against the marines.
Italy has also recalled its Ambassador to India Giacomo Sanfelice to express its unhappiness over the charge sheet being filed against the marines. The Italian Prime Minister had earlier called up Singh in March, warning him against setting a "dangerous precedent" with the prosecution of two Italian marines in India.
"Any attitude from the Indian side that is not fully in line with international law...risks creating a dangerous precedent for international peacekeeping and anti-piracy missions," Monti was quoted as saying to Singh during the March 7 conversation.
"The alleged incident, the circumstances of which still have to be clarified, occurred in international waters and jurisdiction is therefore only Italian," Monti had told Singh, according to a government statement.
Singh had reportedly told Monti that he wanted "to avoid tensions between India and Italy".