Norwegian Navy frigate HNOMS HELGE INGSTAD (F313), displacement 5290, commissioned 2009, complement 120, armament missiles, torpedoes, guns, helicopter. The frigate's 137 crew members were evacuated amid fears that it may sink.
Meanwhile, the 62,000-tonne oil tanker, which was flying the Maltese flag but is owned by a Greek shipping company, was only slightly damaged and none of the 23 people on board were injured, the rescue centre said.
Up to eight people were injured in the collision in the Hjeltefjord near Bergen, Norway, when the KNM Helge Ingstad crashed into a vessel from Malta.
The tanker had left a nearby oil shipments terminal operated by Equinor carrying a cargo of North Sea crude oil.
It was being towed out of the harbour when it somehow managed to ram the frigate.
Rear Admiral Stensoenes said the cause of the accident was not clear and the Navy would wait for the findings of Norway's Accident Investigation Board.
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He said: "It is taking in more water than they can pump out".
Johan Marius Ly of the Norwegian Coast Guard said the 442ft frigate, which had recently taken part in the North Atlantic Treaty Organisation drill Trident Juncture, was listing, adding: "We have been told that there is a leak from the frigate. The frigate moved to an inshore location and was listing heavily at 11:30am, amidst emergency efforts to prevent the vessel from sinking".
A small oil slick has surrounded the ship following the collision.
Although the tanker was undamaged, the £465 million frigate took on large quantities of water and was in danger of sinking when the captain took her into shallower water before running her aground.
"The armed forces is now reviewing all the means available in the region to assist the KNM Helge Ingstad", Lieutenant Colonel Ivar Moen told AFP. Launched in 2007, the warship is named after the famous Norwegian Arctic explorer.
The ship had previously been part of an escort convoy which seized chemical weapons from Syria back in 2013.