The Hamburg Port Authority (HPA) has closed the port to large ships because of a strike announced by the Verdi union over wages, it said on Wednesday.
"Due to the massive restrictions to be expected from the announced warning strikes, the administration has decided to block the Elbe for ships requiring pilotage from around 10 a.m. today until further notice," a spokesperson for HPA said.
From 5.30 p.m. (1630 GMT) onwards, such ships will no longer be able to leave the port because the crews of boats that bring pilots on board container ships are taking part in the protests, the spokesperson added.
Around 18 ships bound for Hamburg will be affected by the move. The number of ships not able to leave the port is more difficult to quantify for logistical reasons.
Verdi plans to continue the protest until Friday at 6 a.m. It has also called on workers at Hamburg airport to walk out as part of the public sector wage dispute. The protests, scheduled to last 24 hours, are to begin with the night shift on March 22.
(Reuters - Reporting by Riham Alkousaa and Matthias Inverardi; Editing by Matthias Williams, Friederike Heine and Jan Harvey)