The major Forties pipeline – which carries crude North Sea oil across land for processing at Grangemouth – is to be closed due to a cracked pipe.
The crack and leak was discovered last week near Netherley in Aberdeenshire.
The pipeline’s owner Ineos said on Monday that, despite pressure being reduced, the crack had extended.
A spokesman said: “The incident management team has now decided that a controlled shutdown of the pipeline is the safest way to proceed.”
The Forties pipeline carries about 40% of North Sea oil and gas.