The "Serenade of the Seas" with a thousand cabins was finally able to resume its route to the popular tourist city, according to Carlijn van Essen, a spokeswoman for the Port of Amsterdam. An oil tanker was also prevented from docking.

"Oil kills, stop cruise ships", the activists spray-painted on the doors of the lock they had tied themselves to, according to footage broadcast live online on their video stream, XRTV.

Police arrived on the scene around 5 pm local time (1500 GMT) to remove eight protesters, according to Dutch news agency ANP.

They were taken into custody but have since been released, and no arrests were made, a police spokesperson told ANP.

The action was carried out by Extinction Rebellion, which has called for an end to visits by the highly polluting vessels to the Dutch city.

Van Essen told AFP that the activists were at two locks in the huge IJmuiden complex, northwest of the capital.

A week ago, 2,000 passengers from another cruise ship had to be evacuated by bus after similar action, Dutch public media NOS reported.

Centre-right party leader and outgoing justice minister Dilan Yesilgoz criticised the action on X, accusing protesters of causing "nuisance" and "great costs to society and entrepreneurs", and of "wasting precious police ressources".

"All it takes is courage," the group replied on the social website.

The group's Netherlands branch wrote that "years of failed climate policies, a planet on fire, successive weather extremes" explained why "concerned citizens want to make themselves heard".

Extinction Rebellion is known for direct action protests such as shutting down bridges over the Thames river in London.

According to a study by NGO Transport and Environment, cruise ships sailing in European waters in 2022 emitted more than eight million tonnes of CO2 -- the equivalent of 50,000 Paris to New York flights.

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