Sharemarket investors sold down all three Australian-listed participants involved in the Banda well, including slashing Hardman's share price by more than 10 per cent. Woodside ended 14c lower at $12.59, Hardman slumped 9c to 77c on heavy volume while Roc Oil fell 1c to $1.42.

Project operator, Woodside, said yesterday the Banda well had intersected a gross hydrocarbon column of 133 metres with 110m of gas and 23m of oil.

"We are pretty pleased, it's a very good result. Of course, the market does not understand it, as it usually doesn't," Mr Ellyard said.

"The market's reacted to the fact there is a lot of gas and they want oil. But what they don't realise is its very large structure and that a 23m oil leg means, we think, similar sorts of volume as we got in Chinguetti, which is more than 100 million barrels, plus there is at least a couple of tcf (trillion cubic feet) of gas."

Mr Ellyard added that the market should not be disappointed with the gas because there was domestic demand and, in only 300m of water, could be easily developed.

"This is also the first significant gas discovery in Mauritania, which currently relies on imported fuel for all its energy needs," he said.

John Doran, managing director of Roc Oil, said the gas discovery possibly heralded a new oil and gas province.

"It is increasingly hard to avoid the view that the drilling successes which the Joint Venture has experienced in the last 15 months represent the birth of a new petroleum province," he said.