Enter South African Breweries (SAB) and Castlebeer.

The southern giant opened a plant outside Nairobi in October and now threatens to encroach on KBL's home turf.

"The perception is correct. We are fighting," KBL group managing director Michael Karanja told Reuters.

Two factors intensify the competition -- a mysteriousbattle-of-the-billboards and a decision by Kenya Breweries to launch its beers in South Africa.

Somebody, somehow, has been sabotaging adverts for beer.

Both companies are quick to deny responsibility for a recent spate of attacks on KBL and Castle billboards in Nairobi, buying newspaper space to highlight that they are being victimised.

And both companies have moved to seize the moral highground, pointing out that they alone have refrained from accusing the other of doing the damage.

"Truth and Reconciliation: Let the facts be known," KBL said in a full-page advert in the East African Standard that pointed to events at the southern end of the continent.

Below were a series of pictures of defaced KBL hoardings and the words: "Persistent insinuations in the press regarding damaged and defaced beer billboards compels us to respond."

"Defaced but not demotivated," countered Castle above a similar picture of a damaged Castle advert.

A deeper point of conflict is the Kenyan brewery's attempt to sell Tusker in South Africa.

Karanja accused SAB of deliberately blocking its entry into the South African market by registering a brand that features Tusker's logo. He said his company would go to court.

"They must be reasonable. We don't use those tactics to try and stop them. If we wanted to we would have registered Castle (in Kenya)," he said.

Allen Mc Innes, Castle Kenya's sales and distribution manager, denied Castle engaged in unfair competition, arguing that Kenya Breweries had registered around 100 names on its turf in an apparent attempt to block other brewers.

SAB controls 98 per cent of its domestic beer market and dominates the African industry.

Not only that, it has powerful positions in Poland, Hungary, Romania and Slovakia, is building a plant outside Moscow and holds nearly five per cent of China's booming market.

SAB has also dominated the Tanzanian market since 1993 when it bought the state-owned brewer. It now expects rapid expansion in Kenya having opened a plant in Thika as Castle Brewing Kenya Ltd in partnership with local businessmen.

The Thika plant can produce up to 30 per cent of the 2.2million hectalitres (48 million gallons) consumed annually in Kenya, said Mc Innes.

Castle's distribution and marketing are aimed at the Nairobi area, which accounts for 60 per cent of the Kenya market.

"If you take over a yearly volume (in Kenya) we have perhaps only got about two per cent," said Mc Innes. "But if you just take our volume for last month only on a monthly basis... we have perhaps got between five and seven per cent."

"Any business would like to have as much of the cake as possible and fortunately the market is big enough for two breweries to enjoy a decent slice of the cake," he said.

KBL says it has 97 per cent of the Kenya market and 50 per cent of Uganda. In Tanzania, KBL controls 9.5 per cent, a figure that it hopes will rise after it opened a plant in the northern town of Moshi earlier this year.

Bright yellow billboards are a vital weapon in the war.

Tusker's adverts -- captioned "my country, my beer" -- are a naked appeal to patriotism.

Castle's adverts feature an ice-cold can, tipped temptingly to one side.

Lack of disposable income stops many Kenyans from touching the demon drink. Only 10 per cent quaff beer while another 10 per cent drink cheaper home-brewed alcohol such as "chang'aa".

The irony for Kenya Breweries and South African Breweries is that the majority of the population are innocent bystanders to the beer war. Most Kenyans are teetotallers.