Norway restarts key gas plant, output to stay down Friday

(Adds Kollsnes restart, Skarv outage)

OSLO, April 2 (Reuters) - Norway restarted its biggest gas processing plant on Thursday after an unexpected outage but production will only be ramped up slowly and will remain down on Friday, gas system operator Gassco said.

Production at Kollsnes on Norway's western coast was interrupted late on Wednesday, cutting Norway's gas capacity by a quarter and pushing British gas prices sharply higher.

Despite the restart, output from Norway, which supplies a fifth of the European Union's gas needs, will be down by 32 million cubic metres on Friday, about a tenth of the capacity, due to the lingering effect of the Kollsnes outage and a fresh problem at BP's Skarv field.

On Thursday, output was down by 87 million cubic metres.

Kollsnes processes gas from some of Norway's biggest fields, including Statoil (LSE: 0M2Z.L - news) 's Troll. (Reporting by Balazs Koranyi; Editing by Pravin Char and David Evans)