ATHENS (AP) — Greek seamen are extending their strike for a further 24 hours, leaving the country’s mainland and islands without ferry services until Friday morning.

Ferries have remained tied up in port since 6 a.m. Wednesday for what was to have been a one-day strike. But the union, the Panhellenic Seamen’s Federation, announced in the afternoon it would extend the strike for a further 24 hours.

The union called the strike to protest pension cuts, poor working conditions and changes that would open domestic sea transport to non-European Union flagged ships. It called for new collective labor contracts with pay rises, and for the prompt payment of salaries already owed to seamen.

The union said it was adding an extra day to the strike — “with a prospect of escalation” beyond that — because the Greek government had offered no solution to their sector’s problems and met none of their demands.

Ferries are vital to the nation with the EU’s longest coastline. Only the larger Greek islands have airports and sea transport is the only link that many of the 200 inhabited Greek islands have with the mainland for the transport of people and goods.

Workers on a boat clean the sea in front of docked ferries during a 24-hour strike by the Panhellenic Seamen’s Federation (PNO) to oppose the government decision of opening domestic sea transport to non-EU ships, at the port of Piraeus near Athens, Wednesday, April 18, 2018. (AP Photo/Petros Giannakouris)