An animal rescue team volunteer looks at an oil covered swan after a freighter punctured its hull while mooring in the Rotterdam harbour

Animal rescue workers on Monday were frantically cleaning hundreds of birds after an oil spill in the Rotterdam harbour at the weekend, when an oil tanker hit a jetty dumping some 200 tonnes of bunker fuel.

The Norwegian tanker Bow Jubail on Saturday crashed against a jetty in western Europe's largest port, spilling the heavy bunker fuel into the section of the reserved for offloading petroleum, west of the city.

"We are currently hard at work cleaning hundreds of , including swans," said Anneke Heinecke of the Dutch water management agency Rijkswaterstaat.

"Many of the birds are covered in oil and it's not easy to catch and clean them," Heinecke told AFP.

The Rijkswaterstaat, together with other animal aid organisations, set up an "animal hospital" Monday capable of cleaning some 500 birds, she said.

In total, more than 300 birds have been captured and were in the process of being cleaned, Heinecke said.

By Monday afternoon 100 tonnes of the fuel had been cleaned up with the operation expected to take "several more days," the Port of Rotterdam said.

"Six special cleaning ships are active in the area," the harbour said in a statement.

"It will take several days for operations to wrap up," it added.

Dutch news reports said the Bow Jubail belonged to Norwegian oil and chemical transporter Odfjell, with the Port of Rotterdam adding it is "holding the owner responsible" for the accident.

The Dutch Safety Board—which looks into industrial accidents—also announced it was going to the site to do a preliminary probe.

One of the largest spills in the Rotterdam harbour happened in 2007 when a ship broke its mooring and crashed against a quay during a heavy winter storm.

The crash ruptured pipelines on the Maasvlakte Oil Terminal, spilling some 800 cubic metres of oil into the harbour.

Damage from that spill ran into millions of euros and it took more than a month to clean up, Dutch news reports said at the time.