Oil explorer Cairn Energy and its joint venture partners have discovered oil at a well offshore Senegal and further exploration work nearby is already planned, the company said on Tuesday.

The companies encountered 29 metres of net oil bearing reservoir at the FAN-1 well, located around 100 km off the coastline and 1,427 metres deep.

"We have encountered a very substantial oil bearing interval which may have significant potential as a standalone discovery," said Cairn Energy chief executive Simon Thomson.

Cairn Energy has a 40 per cent interest in three offshore blocks in Senegal, while ConocoPhillips has 35 per cent, FAR Ltd 15 per cent and Senegal's national oil company Petrosen owns 10 per cent.