Shares in Tullow Oil have surged after the company announced its second oil discovery in Ghana, making the country home to Tullow's biggest find to date.

In a statement yesterday, the company said it had discovered a "significant light oil accumulation" in the Hyedua-1 well on its Deepwater Tano licence off Ghana.

The news comes just two months after Tullow announced its first discovery in Ghana, in the Mahogany-1 well, and confirms a belief the company asserted at the time that the oil-bearing structure may extend into the neighbouring block.

Tullow finance director Tom Hickey said yesterday that the discovery had far exceeded the company's expectations.

It is estimated that the two fields combined may contain as much as 800 million barrels, which at today's oil price of about $70 a barrel equates to a value of about $56,000 million.

Tullow has a 49.95 per cent interest in the Deepwater Tano licence, the most recent to be drilled, and 22.9 per cent in the West Cape Three Points licence. The other partners are US groups Kosmos and Anadarko Petroleum and the Ghana National Petroleum Corporation.

Analysts welcomed the findings, in particular the news that the two blocks were connected.

Davy analyst Job Langbroek said in a note to investors: "The announcement should strongly support the Tullow share price in the current difficult markets and clearly gives a great deal of comfort that earlier expectations of the scale of the Mahogany discovery were not misplaced."

Tullow has made no secret of its desire to strike it big in Africa, and last month announced plans to scale back activities in the North Sea to focus on Africa.

Mr Hickey said yesterday Tullow would now drill three more wells in the area before the end of the year to ascertain the field's full potential, although after only two wells it has already been declared commercial

Tullow shares closed up 8 per cent at €7.19 in Dublin yesterday, while in London, where the stock is more actively traded, it rose 4.4 per cent to £4.83.

Separately, Mr Hickey said he does not expect the Congolese government to address the issue of its licence in the Democratic Republic of Congo for a while.

It was reported last week that the licence was to be revoked by the new minister for hydrocarbons. Mr Hickey has insisted the licence is legal.