The minimum salary is currently €557, based on 14 monthly payments a year (including extra 'months' at summer and Christmas).

Asked by journalists after the day's regular weekly cabinet meeting, about public calls by the Communist Party - which forms part of the minority Socialist government's support base - for the minimum to be increased to €600 in January, the minister at first said only that this “was not a subject touched on” at the cabinet meeting.

“The government will keep to what is in the government's programme, which is presenting to employers and trade unions an amount for the SMN for 2018 ... in line with the objective set for this parliament of reaching 600 euros at the end of the [current] parliament," he said.

Last week, in Guimarães, the Communists' leader, Jerónimo de Sousa, said there were "reasons for concern" because, he said, "on various matters there is no response to the legitimate expectations of workers".

He cited the minimum salary as among these and said that the party would press for an "extraordinary increase in the national minimum salary to 600 euros, in January of 2018 so as to contribute to the improvement of living conditions and the stimulus to economic development."

Tensions among the three left-of-centre parties that support the government have been growing in recent weeks in the run up to October's local elections, in which they are not putting up joint candidate lists but instead vying for votes.

The next national legislative election must be held no later than October 2019.