Three of Italy's main unions called for a nationwide ports strike to start on Friday after two workers died overnight in a port near Venice.
The call for a strike which could paralyse the country comes as Italy debates workplace safety following a fire last month at a ThyssenKrupp steel plant in Turin which killed seven workers.
Labor federations CGIL, CISL and UIL said in a statement they "strongly protest following incidents which reached unbearable levels in 2007 and, unfortunately, continue".
They called for for an immediate strike. It was not immediately clear how big the strike would be or how long it could last as unions said its terms would be set locally.
"The protest is aimed at those companies which do not guarantee work safety," the unions said.
Two workers died early on Friday after being overcome by fumes while cleaning a ship's grain hold at Porto Marghera near Venice.