Last week, the Dana Petroleum-led JV decided to deepen the well by a further 203m to a new total depth of 4900m to continue exploring the Cretaceous section where the oil column was encountered.

But today, Hardman said although further sands were encountered in this deepened section, they were not found to be oil-bearing.

The company said downhole pressure measurements and fluid samples confirmed that the 20m oil column was present in good quality Cretaceous age reservoir sands.

“The discovery of oil in the Cretaceous zone in Block 7 extends the oil fairway within the northern region of Mauritania,” Hardman chief executive Simon Potter said.

“While not likely to be commercially significant at this location, it offers encouragement for future exploration within this still relatively new oil province.”