Italian lower house of Parliament's Defence Committee members met two marines, Massimiliano Latorre and Salvatore Girone, who are accused of killing two fishermen off southern India in 2012.
"The two informal meetings (on Tuesday) represented an opportunity to show the Defence Committee's interest in an unwavering solidarity over the incident," said a statement from Parliament.
A court in the Hague was in October due to begin considering the long-running case which strained bilateral ties and prompted Italy to seek international arbitration in 2015.
The fatal shooting in February 2012 of the two unarmed fisherman by Latorre and Girone off Kerala as they guarded an Italian oil tanker sparked a diplomatic incident between Italy and India.
Italy alleges the incident took place in international waters during a UN backed anti-piracy mission.
Girone and Latorre, who have not been charged over the killings, claim they thought the unarmed fishermen were pirates.
Both marines were allowed to return to Italy after the Hamburg-based International Tribunal for the Law of the Sea in August 2015 ruled India had no jurisdiction in the case and referred it to the International Court of Justice in The Hague.
The marines have been allowed to stay in Italy pending the Hague court ruling.
(Our News Desk can be contacted at firstname.lastname@example.org)