Tullow Oil, said Monday that it has discovered a major new oil field off the coast of Ghana. Its shares surged as a result.

Tullow found light oil of 33 to 36 degrees gravity on the American Petroleum Institute scale in the Tano area off Ghana, the company said.

Light oil is more useful than so-called heavy oil because it is closer to the petrol and diesel used by industry, motorists and homeowners.

Wells in the Tano area have yielded a string of discoveries, including the Jubilee field, establishing Ghana as a country with significant oil reserves.

Tullow also has positions in the Atlantic Ocean off the coast of Ivory Coast, Liberia and Sierra Leone and is planning to drill a number of wells on its licences in these countries in the next 12 months.

"This is a big well and a big result for Tullow. We've got here a very substantial light oil discovery," Angus McCoss, the exploration director at the company, said.

"It's really looking to be another transformational oil field for Ghana."

Tullow is the operator of Deepwater Tano where its partners include Anadarko Petroleum, Kosmos Energy and Ghana National Petroleum Corporation (GNPC).

Tullow owns a 49.95pc stake in the Tano licence.

Shares in Tullow closed up 4.5pc at €14.76 yesterday. This gave the company a market capitalisation of €13.1bn - almost €2bn more than CRH, the next largest company listed on the ISEQ.

Tullow is Europe's largest independent oil explorer by market value.

Targeting

Tullow had been targeting a 1.4 billion-barrel find in the Owo-Tweneboa-Ntomme area off Ghana, according to a July 1 company presentation.

"We are going to be partitioning the greater Tweneboa area into a very substantial highly pressured oil field at Owo and the neighbouring major oil and gas field at Tweneboa," Mr McCoss said.