A man died and another was seriously injured after an accident at a shipyard operated by Italy's Fincantieri in the port city of Ancona, the shipbuilder and police said on Wednesday.
The accident occurred late on Tuesday when a fire broke out as the two workers were carrying out welding work on a vessel.
Police are investigating the cause of the blaze, which local unions said may have been due to a fault involving a welding machine.
Both men were employed by a subcontractor, Fincantieri said.
The victim was a 54-year-old Tunisian who died from severe burns, a local union official said, while the critically injured worker is a 29-year-old Bangladeshi.
Local media reported that he is due to be transferred from Ancona's regional hospital to a specialist burns unit in the Tuscan city of Pisa.
Italy's main metalworkers' unions - Fiom, Fim and Uilm - staged a protest at the shipyard and began immediate eight-hour strikes covering the day's shifts.
National unions called for a two-hour strike across all Fincantieri's shipyards from Wednesday.
"Safety culture needs to change, it is too often viewed solely as a business cost," a local union statement said, calling fro greater investments in training and protective equipment.
The unions also called for a review of Italy's contracting and subcontracting practices, saying workplace accidents were more common in places where subcontractors worked.
(Reporting by Giulia Segreti in Rome, editing by Gavin Jones)