ENQUEST is underlining its faith in the potential of the Kraken heavy oil discovery east of Shetland by acquiring its third stake in the find.

The oil and gas independent has agreed to acquire an additional 15% in the blocks containing Kraken from First Oil for up to $144 million (£88.9m).

The deal will allow EnQuest to increase its holding in Kraken to 60%, for which it has agreed to pay up to almost $500m (£308m) in total.

On January 9, Enquest agreed to acquire a 20% stake in Kraken from Canamens for up to $90m (£55m). A fortnight later it agreed to buy a further 25% from Nautical Petroleum for up to $240m (£148m). The company's chief executive, Amjad Bseisu, described Kraken as one of the most exciting development projects in the UK North Sea.

EnQuest will pay the maximum $144m to First Oil if Kraken is found to contain more than 166 million barrels oil equivalent reserves.

It expects to use tax breaks that are available for investment in the North Sea to reduce the total cost.

Mr Bseisu noted: "As with our purchase of a 25% interest from Nautical and based on the maximum carry, the cost per barrel to EnQuest is $6/bbl before tax effects."