The CGTP's leader, Arménio Carlos, announced the protest at a meeting of the national leadership in Lisbon, saying that it was to call for “the valuing of work and workers, to demand a deepening of the course of restoring and winning rights and to combat injustices and inequalities”, among other demands.

The move comes after Portugal’s Communist Party, with which the CGTP has close links, did poorly in the 1 October local elections – the first electoral test for the party since it decided in late 2015 to sign an unprecedented a deal to prop up a Socialist minority government. In the elections, the PCP lost control of several long-held bastions.

Another far-left party, the Left Block, has also signed a deal to prop up the government in parliament but was less affected by losses in the local elections, since it controlled no councils.

Political analysts have said that in the wake of the local elections communist-leaning trade unions would probably now step up action in workplaces and on the streets, in an extra-parliamentary show of strength.

As part of his announcement on Tuesday, Arménio Carlos also unveiled a campaign against casual non-traditional forms of employment, including a national petition that, he predicted, would be “a milestone in the combat against precarious work”.