The discovery has been named the Fife field. Premier owns a 15 per cent stake and Amerada Hess, the US oil company, owns the balance.
The two partners have also been granted exploration licences for two adjoining blocks, 39/1 and 39/2, as the field extends into them. The licences were granted by the Department of Trade and Industry outside the normal bidding rounds following an application by the two companies.
Fife was discovered in block 39/26a, which already contains a producing field, Angus, in which Premier has a 6 per cent stake.
The company said it was still too early to estimate Fife's potential, but analysts believe it could contain recoverable reserves of about 50 million barrels of oil.
Amerada, the operator, has so far drilled just one well but several more are planned in the next six months to appraise its size.
However, the initial results looked encouraging, with a flow rate of 11,540 barrels per day on a 42/64-sized well-drilling choke. The find was made in relatively shallow waters at 231 feet, which could facilitate its development.
Premier's shares, which have been severely hit by its lacklustre exploration success in the past two years, gained 1.5p to 16.75p yesterday, valuing the group at pounds 82m. They have collapsed from a high of 75p over the past two years. Over 12 months they have slumped from a peak of 45p.
Charles Jamieson, chief executive, said: 'It is gratifying to have had such a significant discovery and to have consolidated Premier's licence position in a wide area around Fife and Angus.'
The company, which currently produces 13,500 barrels of oil per day, has a 12.5 per cent interest in Wytch Farm, the Dorset oilfield.
Last month, it reported a 49 per cent increase in taxable profits to pounds 26m for the half-year to 30 June.Reuse content