WINDHOEK, Khomas (AFP) - Finding large quantities of oil in Namibia is only "a matter of time", the head of Brazilian oil firm HRT said on Thursday, playing down lacklustre initial drilling results.

The chief executive of HRT, Milton Franke, said he was confident Namibia would become the latest in a string of major Africa crude producers, despite around a dozen exploratory wells largely coming up dry.

HRT discovered some oil in a Walvis Basin well off Namibia's Skeleton Coast earlier this year but not in commercial volumes.

"HRT believes that finding oil in Namibia is a matter of time. Both basins, Walvis and Orange, have good source rocks, in the oil generation window," he said.

Drilling at HRT's third test well is now underway, with results expected in mid-October, he added.

Mr Franke said they had learned from experience in Brazil that patience is needed.

"We see that in Campos Basin the first commercial oil discovery came with the drilling of the ninth well. Today it is the largest producer of the country."

Similarly, in Brazil's Santos Basin, around 50 wells were drilled before major energy discoveries, he said.

In Namibia offshore exploration began in the late 1960's and resulted in major gas finds, but so far no oil.

But there are high hopes that Namibia could replicate crude discoveries in neighbouring Angola to the north, Africa's second-biggest producer of crude, after Nigeria.

"There is much work to do in Namibian basins exploration. If it is not HRT that will come up with the first oil discovery, it will be another major or independent oil company."

The company operates 10 offshore blocks in Namibia and its exploratory drilling programme is worth around US$200 million (S$253 million).

Mr Franke became CEO in May, after serving as the firm's production director and working with Brazilian state-backed oil major Petrobras.

Other companies with exploration licenses in Namibia include Spain's Repsol and Petrobras.