The Rosebank discovery, which lies some 130 km (80 miles) northwest of the Shetland Islands, could hold more than 300 million barrels of recoverable oil, according to the estimates of its former operator Chevron.

"We believe there is more value to capture in Rosebank, including the opportunity to reduce development cost," Hedda Felin, Equinor's senior vice-president for UK and Ireland, said in a statement.

Equinor did not provide Rosebank development cost estimates, but consultancy Wood Mackenzie said last year it could cost more than $6 billion (£4.7 billion).

Equinor and Suncor Energy have each 40% interest in the Rosebank project, while Siccar Point Energy has the remaining 20%.

The Norwegian company acquired 40% stake in the project from Chevron last year as the U.S. oil major focuses on developing its shale assets.

(Reporting by Nerijus Adomaitis, editing by Gwladys Fouche and Louise Heavens)