The company said it has found an additional 43 metres of potential oil pay in its Ngamia-1 well in northern Kenya, which is operated by Africa Oil's partner British exploration firm Tullow.

"The net oil pay logged in Ngamia-1 is more than double that of any of Tullow's east African exploration wells drilled to date," Tullow country manager Martin Mbogo said in a statement.

Kenya and its neighbours in east Africa, as well as the Horn of the continent, have become a hot spot for oil and gas exploration in recent years, spurred by new finds in countries including Uganda, Tanzania and Mozambique.

The Ngamia-1 well in Kenya Block 10BB, was drilled to a depth of 2,340 metres and will now be suspended for future flow testing. The commercial viability of the find has yet to be ascertained.

In a statement, Tullow country manager Martin Mbogo said the volume of oil pay has "substantially exceeded expectations".

The well has more oil-bearing sands than the company's Ugandan wells, which it determined were commercially viable in 2006.

Tullow is moving the Ngamia-1 drilling rig 31 km west to spud its second Kenyan well this year, known as Twiga-1.

When that well is complete, it will return the rig to the Ngamia-1 site for work that will determine the commerciality of its first discovery.

Mwendia Nyaga, former CEO of the National Oil Corporation of Kenya, who works as an oil and gas consultant, said he expects it will be at least 12 months before Tullow will know whether the Ngamia-1 well can move to production.

"What we've seen is very promising, but there are no guarantees," he told Reuters.

Uganda discovered commercial hydrocarbon deposits along its border with the Democratic Republic of Congo in 2006, and Tullow says reserves of 1.1 billion barrels are confirmed in place and believes there are a further 1.4 billion barrels left to find.