Ticket staff walked off the job over the same issue just four days after.

National rail company Comboios de Portugal said almost all international train services were canceled while national service would suffer delays as well as cancelations throughout the day.

The National Union of Train Conductors (SMAQ) said participation in the strike by its members was “total”.

The debt-ridden railway company had been hit by a string of strikes since February. Workers are angry that an agreement on overtime pay they signed with the company earlier this year still has not come into force.

The company argues that the agreement can only be applied once it gets permission from the finance ministry, which is under pressure to rein in Portugal’s huge public deficit.

In April Portugal became the third euro zone country to request a multi-billion-euro bailout from the European Union and the International Monetary Fund after Greece and Ireland last year.