SABMiller PLC is poised to announce a deal to acquire Colombian brewer Grupo Empresarial Bavaria, South America's second-biggest beer producer, for about $6 billion, a move that would help it secure a foothold in the fast-growing South American beer market.

An agreement could be announced as soon as today, according to people familiar with the situation. But the two sides were still negotiating details, and the deal could still fall apart, these people warned.

Yesterday, SABMiller's stock swung on rumors of an imminent deal, ending down 0.3 percent at $15.52 in London trading, while Bavaria's rose 4.5 percent to $21 in early trading on the Colombia Stock Exchange.

Under the structure being finalized, SABMiller would acquire the Colombian company in a cash-and-stock deal.

SABMiller would use $3.5 billion of its own shares to acquire the Bavaria stake held by the family that controls about 70 percent of the Colombian company. The remainder of the publicly traded shares would be purchased for cash. The London-based brewing giant, whose brands include Miller, Pilsner Urquell and Castle, a South African brew, also would assume Bavaria's debt, totaling about $2.3 billion.

The deal would make the family that controls Bavaria among the largest shareholders in SABMiller, with a stake of about 17.5 percent. Altria Group Inc. would still be the largest shareholder in SABMiller, with 26 percent of the company.

For SAB, a deal would mark the culmination of a year-long effort to break into South America, where rivals InBev and Heineken NV already have significant investments. Founded in 1889, Bavaria, controlled by Colombian billionaire Julio Santo Domingo, is considered the most attractive of the remaining beer assets in the region, with leading positions in Colombia, Ecuador, Panama and Peru.

Its brands -- Aguila, Cristal, Pilsener and Atlas -- have global export potential and could help SAB offset sluggish growth in Western Europe and North America.

Bavaria's total sales last year topped $1.9 billion, up 13.2 percent from 2003.

However, an SAB-Bavaria tie-up also faces challenges. While it would help SAB take on its rival InBev, the No. 1 brewer in Latin America, catching up to InBev won't be easy. InBev, created when Belgium's Interbrew merged with Brazil's Companhia de Bebidas das Americas, or AmBev, in 2004, dominates Latin America through a stronghold in Brazil, selling 70 million hectoliters of beer (about 1.85 billion gallons) annually in Latin America, compared with Bavaria's 30 million hectoliters (about 792.5 million gallons). Meanwhile, InBev already has a huge distribution network in South America and has been expanding into Bavaria's main markets in recent months.

Analysts also warned that a deal could prove risky since a sizable chunk of Bavaria's business is in politically volatile Colombia. There also is little geographic overlap between the two groups, making it difficult for SABMiller to squeeze synergies.

People familiar with the situation said SABMiller had outmaneuvered Heineken because the Santo Domingo family had been attracted by SAB's experience in other emerging markets such as Eastern Europe, South Africa and Central America. SAB also was willing to structure the deal in a way that appealed to Julio Santo Domingo, who wants to retain some control over a combined group, these people said.

"SABMiller will try to pitch this as a merger rather than a takeover because they think it will make the family happy -- but it will very much be a takeover," said a person familiar with the deal.

Susanna Howard of Dow Jones Newswires in London and Diana Delgado in Bogota contributed to this report.