The Italian trade union USB filed a legal complaint against a plan by gas grid operator Snam to set up a new liquefied natural gas (LNG) terminal in the Tuscan port of Piombino, it said in a press release on Friday.
USB alleged Snam had committed serious "environmental crimes" while performing works to build the terminal.
USB criticised in the statement the choice to set up the terminal in an area already polluted by an old steel plant, saying regasification processes would increase pollution levels even further and cause "serious and irreparable injuries."
Snam declined to comment on the issue.
Last year, the Italian government mandated Snam to buy the terminal as part of a broader effort to increase the country's LNG import capacity and offset dwindling Russian gas supplies.
Under the government's plan the floating storage and regasification unit (FSRU) should be operational by April when new LNG supplies are expected from several African countries.
USB said its legal complaint was filed to the Livorno prosecutor's office.
In November, Piombino city administration filed a legal challenge against the LNG terminal claiming risks to safety, the environment and local businesses. That challenge included a "precautionary request" to suspend the works to set up the FSRU.
An Italian administrative court in December ruled against the request for a precautionary halt on works for the terminal and scheduled a new hearing on March 8 to assess longer-term safety issues relating to the floating terminal.
(Reuters - Reporting by Alessandro Parodi and Francesca Landini, Editing by Aurora Ellis)