If the merger was to go ahead between Belgian company Interbrew, owner of the Stella Artois and Beck's brands, and South African Breweries, which makes Pilsner Urquell and Amstel, it would likely lead to a spate of rival mergers in the industry.
An Interbrew spokesman said the company was still reflecting on today's reports and may make a statement later today.
According to a report in the Financial Times, an offer could be made as early as December 3, with a figure of more than £4bn being mooted. However, reports on Reuters say that leaked papers regarding the bid were simply routine reviews of rivals.
If the merger did go ahead, the only bigger brewer in the world, by volume of beer produced, would be Anheuser-Busch, owner of the Budweiser brand.
SAB owns and operates 85 breweries in 22 countries, employing more than 31,000 people, and was listed on the London Stock Exchange in 1999. Interbrew is in the process of selling its Carling lager brand, after its takeover of Bass Brewers, in order to meet UK competition regulations.
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