Oil and gas explorer Cairn Energy has bumped up the resource estimate for its oil field off the coast of Senegal by 20 per cent.
The FTSE 250-listed company increased its estimated oil reserves at the field to 385m barrels of oil after positive drilling results.
"We are delighted with the results to date of our multi-well evaluation programme offshore Senegal, which has confirmed the scale and extent of the significant resource base in this world class asset," Simon Thomson, chief executive of Cairn Energy, said.
However, shares in Cairn Energy fell as much as 4.6 per cent to 187.7p at the open. Analysts at FirstEnergy said the market reaction was slightly negative because some investors may have expected a larger increase.
It comes as the Edinburgh-based company's pre-tax losses from continuing operations for shrank to $497.8m in 2015, down from $559.1m a year earlier.
Cairn, which doesn’t produce any oil, said its losses were dominated by a $319m writedown on the value of its remaining 10 per cent stake in Cairn India.
Cairn is currently locked into a tax dispute with the Indian authorities.