That is despite the fact that shipping companies have been able to divert some cargoes through other of the country's ports, she explained.

“So far as the reduction in the turnover of [shipping] operators at the port of Lisbon goes, the estimate that has been put forward is of 300,000 euros a day," Vitorino said in a break from a conference in Lisbon. “However, we have done the sums at the national level, with the transfer of cargo and increase in costs of other ports and, considering some of the direct losses for companies that use the ports, we have reached the conclusion that the loss at the national level is at least 100,000 euros.”

Arguing that the strike - which, she noted, forms part of a conflict that has been going on for four years - brings into question the “sustainability of the port of Lisbon” and “affects the national economy”, the minister said that “all right is never on one side but there are limits that cannot be overstepped."

The new board of the state-owned company that runs the port, she said, has been tasked with restoring its viability by all legal means.

The striking dockers gathered in the port on Tuesday as police officers moved in to facilitate the withdrawal by shipping operators of containers trapped in the facility for about a month, since the current strike started.

The president of the Dockworkers' Union described the announcement by the port company of mass redundancies and the presence of police officers as “psychological terrorism” and an “attack on the rule of law”.

The redundancy announcement came after the union on Friday rejected a fresh proposal for a new collective employment contract for the dockers.