A unit of Thai Beverage has emerged as the only prospective bidder for state-owned shares in Sabeco that has declared that it could lead to it owning 25 percent or more of Vietnam’s biggest brewer, the Trade Ministry said on Monday.

The auction of up to 54 percent of Sabeco worth at least $5 billion, in what is set to be Vietnam’s biggest privatization, offers brewers access to a fast-growing market with a youthful population and beer drinking culture.

Investors who want shares that would lead to an ownership of 25 percent or more in Sabeco have to inform the local authorities and publicize the information a week before the auction date, which is set for Dec. 18, according to the rules of the offer.

Other brewing groups including Anheuser-Busch InBev and Kirin Holdings have been preparing to bid for a stake, people familiar with the matter have said.

But the trade ministry said in a statement on its website that as of 1100 GMT on Monday the one prospective investor which has registered an interest in buying 25 percent or more of Sabeco that has publicized the information is Vietnam Beverage Company Limited.

Vietnam Beverage Company Limited is owned by Vietnam F&B Alliance Investment Company, which is 49-percent owned by BeerCo Limited, an indirect but wholly-owned subsidiary of Thai Beverage, official documents about the companies showed.

Foreign ownership in Sabeco is limited to 49 percent. That means overseas bidders can only bid for a minority stake of as much as 39 percent as foreign entities already own 10 percent.

Lack of control and the unorthodox way in which the Sabeco stake is being sold could put off some possible bidders, bankers, investors and lawyers familiar with the matter said.

The Vietnam trade ministry, which represents state shares in Sabeco, said foreign investors can link up with Vietnamese firms to buy shares in Sabeco, but have to comply with local laws and regulations.