This brings the total gas in place in Area 4 to 87tcf.

The Italian company and its joint venture partners for the project are putting together a final assessment of the discovery and planning an appraisal program.

The Agulha well was the tenth drilled in Area 4, where the company has enjoyed 100% success.

It encountered 160m of net wet gas pay in good quality Paleocene and Cretaceous reservoirs.

The discovery puts the drilling program for 2014 in good stead, with another three wells to be drilled in the same area.

According to Reuters, the company could sell down another 10%, according to Eni group chief executive Paolo Scaroni.

"If some buyer of gas shows interest … we're ready to sell another 10%," he was reported as saying.

He added there were no plans to sell down its full 50% stake in Area 4.

Eni recently sold a 20% stake in the company to Chinese company CNPC.