On Tuesday the rig spilt 1.75 tonnes of hydraulic oil into the ecologically fragile Barents Sea after which Statoil said it voluntarily shut the rig’s operations down until the cause is determined.

The Eirik Raude has two other leaks during February. While drilling an exploration well for Norsk Hydro it had two emissions which, while not classed as environmentally damaging, both violated the ban on emissions into the ocean, according to the Norwegian Pollution Control Authority.

This latest leak has caused pollution according to the NPCA.

The Barents Sea - rich in fish stocks with a fragile, cold water ecology - is believed to have vast oil and natural gas reserves, crucial for Norway to maintain the production levels that makes it the world's third largest oil exporter after Saudi Arabia and Russia

The Norwegian Petroleum Safety Authority (PSA) said that it and the Norwegian pollution control board SFT had jointly ordered the rig to remain shut down while they investigate.

"The authorities take a very serious view of the April 12 discharge, not least since this is the third discharge from the facility during the course of the winter drilling campaign in the Barents Sea," a statement said.