SABMiller, the world's second-biggest brewer, launched a cassava beer Tuesday in Johannesburg, hoping an untapped market of low-income Africans will switch from home brew to commercial beer.

The company says the new product, Impala, is the world's first commercial cassava beer. It will debut in Mozambique and cost 25 percent less than standard barley-based beer.

SABMiller says it is designed to turn poor rural Africans into commercial beer drinkers.

"What we're trying to do is at a 75 percent price point, to attract consumers up from the illicit spirits or the home brews that they would tend to be consuming," Mark Bowman, managing director for SABMiller Africa, said at the launch.

"They're poor consumers generally. This is a rurally oriented product. We want people to gravitate into what is highly aspirational for them, but to some extent unaffordable, with an entry-level beer."

A 550-millilitre (19-ounce) bottle of Impala in Mozambique will cost 25 meticals, about 93 US cents (66 euro cents).

The beer will be made by SABMiller subsidiary Cervejas de Mocambique at its brewery in the northern Mozambican province of Nampula, the company said.

If it is successful there, SABMiller plans to roll cassava beer out to other African countries.

Bowman said the company estimates the informal alcohol market across Africa could be up to four times the size of the formal market.

SABMiller has already been successful marketing a sorghum beer called Eagle in Uganda. Chief executive Graham Mackay said Eagle is now the company's largest-selling product there.