HANOI, Sept 1 - Vietnam's government said it will fully divest from its two biggest breweries and target to raise $2.2 billion over the next 16 months, loosening its tight grip over one of Asia's most sought-after beer markets.

The decision seeks to end years of uncertainty and government flip-flopping about how much of unlisted brewers Habeco and Sabeco the state was willing to part with. The stakes will be auctioned and both domestic and international investors can bid.

Vietnam is Asia's third-largest beer drinker by volume after China and Japan, putting it on the radar of Asian and European brewers keen to exploit changing lifestyles and one of the region's fastest rates of middle-class growth.

Deputy industry and trade minister, Do Thang Hai, said divestment in Habeco, the maker of Bia Ha Noi beer, would be completed within this year and the selloff of shares in bigger rival Sabeco, which brews Bia Saigon and 333 beers, would be finished after the firm lists in 2017.

"All domestic and foreign investors, regardless of their economic structure or sector, can join the bidding," Hai was quoted as saying by the government's news website.

The government owns 81.79 percent of Hanoi-based Habeco and Hai said it would sell 5.77 percent of the firm to Danish brewer Carlsberg, its strategic investor, which currently holds a 15.77 percent stake, while the remaining stake would be auctioned. The aim was to raise 9 trillion dong ($404 million) in total.

Top brewer Sabeco has courted most interest from big brewers, among them ThaiBev, the flagship company of Bangkok's billionaire beer magnate Charoen Sirivadhanabhakdi, who has been making major inroads into Vietnam through investments in dairy, logistics, hotels and retail.

His biggest rival, Boon Rawd Brewery, maker of Singha beer, is expected to enter the Vietnam market via Masan Group, a firm best known for making fish and chilli sauce, after it agreed a $1.1 billion strategic deal in December that included creating a Masan beer subsidiary.

Beer is the top drink in Vietnam, popular both during the daytime and at night, often in large beer gardens. Consumption last year rose 12 percent from 2014 to 3.4 billion litres, enough to fill over 1,300 Olympic-sized swimming pools.

"Investors are very interested in this news due to upbeat performance of Sabeco while local brewery market is still seeing strong growth," said Le Ha, analyst at Vietcombank Securities.

Deputy minister Hai said of the government's nearly 90 percent stake in Sabeco, 53.59 percent will be sold this year to raise 24 trillion dong. The remaining 36 percent would go on sale for 16 trillion dong in 2017 when it lists on a stock market, some eight years after its initial public offering. ($1=22,300 dong)