Public broadcaster NRK quoted the fire department as saying that the KNM Helge Ingstad frigate "is no longer at risk of sinking". The entire 137 person crew was evacuated from the ship.
Norwegian newspaper Aldrimer reports that the oil tanker and maritime traffic authorities repeatedly radioed warnings to the frigate that they were on a collision path, but the Helge Ingstad's captain said it had control.
"It took on a lot of water and there is a real danger that it sinks where it is", an official for the rescue centre added.
Sola TS tanker crashed into Helge Ingstad, tearing a large hole in its side, near the Sture terminal in Oygarden at around 4 a.m (0300GMT) on Thursday.
The crew were evacuated amid fears the vessel would sink.
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".More news: Democratic Socialist Alexandria Ocasio-Cortez Wins Election In a Landslide
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A nearby oil terminal where the Maltese vessel had just loaded its cargo was closed to traffic on 5 November, in turn leading to a halt in production at five oil fields in the North Sea, according to business daily Dagens Naeringsliv.
The KNM Helge Ingstad has been listing dangerously since Thursday's collision in the Hjeltefjord near Bergen.
The tanker, which was carrying a crew of 23, was returned to port for an inspection.
These included the Sture export oil terminal, the Kollsnes gas plant and several offshore oilfields, all of which resumed operation later this afternoon.
Coast guard deputy director Johan Marius Ly said helicopter fuel has leaked from the frigate.
An investigation into the causes of the incident will be launched today, in collaboration with the Defense Accident Investigation Board Norway (DAIBN) and the Marine Safety Investigation Unit (MSIU) from Malta.