“If the green pass mandate is not withdrawn, activity in the port of Trieste will come to a halt,” the dockers’ spokesman, Stefano Puzzer, told Huffington Post.

“Friday’s blockade [in Trieste] is confirmed and it won’t stop there ... [activity in] almost all of Italy’s ports will stop.”

Italy’s green pass shows that the carrier has been vaccinated, tested negative for COVID-19 in the previous 48 hours or recovered from the virus.

From Friday, it will be mandatory for all workers in Italy – in both the public and private sectors – in a move affecting around 23 million people.

Those who go to work without the health certificate risk suspension without pay and fines of between €600 and €1500.

Puzzer said that in Trieste “40 per cent of the dockers aren’t vaccinated, but 850 workers out of 1000 joined the protest”.

“Economic damage, if there is any, will be caused by the stubbornness of the Italian government alone by maintaining this criminal measure,” he added.

Under the new rules, unvaccinated workers can still go to work but only if they undergo a €15 COVID-19 test every 48 hours, at their own expense.

According to Italian news agency ANSA, the interior ministry on Tuesday made a concession in order to keep the port’s essential activities in operation, by offering dockers free swabs until December 31, when the measure is due to expire.

However, the Trieste workers refused the offer, calling instead for the new law to be dropped.

Labour Minister Andrea Orlando also opposed the idea of free tests, saying it reduced the incentive to get vaccinated.

The company that runs the port of Palermo, on the southern island of Sicily, has confirmed it will not pay for its workers to be tested.

Some port companies in Genoa, however, are set to foot the bill for the tests.