Portugal's state-owned national railroad company says only a few scheduled trains are running in the country as staff begin four days of stoppages over the Easter break.

The walkout Thursday forced the cancellation of most suburban services, though some long-distance trains ran as normal. Strikes are also expected to disrupt services through Monday.

The Federation of Transport and Communications Unions says rail company Comboios de Portugal is not paying the full amount due to workers for vacation pay and for working on public holidays.

The company, which is negotiating with the unions, wants to reduce its huge debt burden — in 2013, it stood at more than 4.4 billion euros ($4.8 billion).

Public transport labor groups have long been among the most militant in Portugal.