Cameroonians are among the biggest alcohol consumers in Africa

Intense competition between beer companies has seen 20 million bottles given away since the start of the year.

The prizes, which are revealed beneath the bottle top, include mobile phones, luxury cars and of course more beer.

With a beer costing $1, some punters are using their winning bottle tops to pay for taxi rides.

Big drinkers

"Virtually every consumer of beer in Cameroon has a chance of winning," says local journalist Martin Etonge in the capital, Yaounde.

"Sometimes you go out just for a bottle and you find yourself coming back with four or six free bottles because of winning caps.

"A bottle of beer costs about $1 and that's just over the cost of a township taxi drop."

He says five beer caps would be enough to cover someone's taxi expenses for a whole day.

"Taxi drivers are also using the caps in their fishy deals with the traffic police," adds Mr Etonge. "So they can get off by giving one or two caps to the officers."

He says Cameroon traditionally has one of the highest levels of alcohol consumption in Africa and authorities have not expressed concern about the current trend.

"Nobody seems to be worried about the health implications," he says. "The government is saying nothing about it. But people are certainly drinking more than before."