Portugal’s national rail operator foresees further disruption of services in the next few days, after strike action resulted in well over half of passenger trains on some lines being cancelled on Monday.

Barely more than one in three commuter services in the Lisbon region had run as normal by 4pm, according to CP-Comboios de Portugal, as the capital was worst affected by the action.

Across the country, some 55% of services ran as normal on the first of four days of strike action called by the national engine drivers’ union SNAQ, with members mainly refusing to work the first two hours of their shifts.

Of express trains between Lisbon and Porto, 43% of the fastest Alfa services went ahead as planned, and 65% of the slower Intercidades ones, said CP spokeswoman Ana Portela.

Of regional services, where engine drivers opted to limit their action to a refusal to work overtime, just 15% of trains failed to run.

On Tuesday and Wednesday, CP foresees the cancellation of most suburban services in the Lisbon, Porto and Coimbra areas. It expects more than half of scheduled express services between the capital and Porto to run on Wednesday but only about 25% on Thursday.

The union is marking Friday 5 October, Republic Day, with a total stoppage; only the skeleton service mandated by law will be provided. A recent change in the law means that workers will no longer earn extra for working on a holiday, just time off in lieu.

On Saturday, services should return to normal during the morning.