Shares in Vinamilk , the country's biggest listed firm, hit a lifetime high on Tuesday after local media said drinks maker Fraser and Neave Ltd plans to buy the state's 45 percent stake in a $4 billion deal.
Vinamilk rose 5 percent to a record intraday high of VND123,000 ($5.52) following a report in The Saigon Times, which cited an unidentified chief executive of a foreign fund represented on Vinamilk's board.
The government has instructed its State Capital Investment Corporation (SCIC) to sell out of Vinamilk, a company 11.03 percent owned by F&N subsidiary F&N Dairy Investment.
"F&N has not submitted any offer letter to Vinamilk or the SCIC with regard to any possible offer to purchase SCIC's stake," F&N said in a statement.
Representatives of Vinamilk, or Vietnam Dairy Products JSC, were not available for comment.
Vinamilk has a market value of $6.3 billion, so a $4 billion purchase would surpass SCIC's $2.8 billion stake.
"It's not surprising," said analyst Tran Minh Hoang at Vietcombank Securities. "Vinamilk is one of the top companies in Vietnam with good business results and promising prospects."
An F&N offer would be the latest move by Thai tycoon Charoen Sirivadhanabhakdi to expand in Vietnam and tap strong economic and retail growth in a country of 90 million people.
Charoen, ranked Thailand's second-richest man by Forbes Magazine, controls 88 percent of F&N through Thai Charoen Corp Group (TCC) and his flagship Thai Beverages PCL. TCC subsidiaries have shares in a top Hanoi hotel and own more than 100 Vietnamese convenience stores.
ThaiBev is also interested in Vietnamese state brewer Sabeco, its CEO said in May.
Vichate Tantiwanich, ThaiBev's senior vice president, said no move had been made for a larger share of Vinamilk.
"We already have a stake through F&N," he told Reuters.
Increased interest in Vinamilk has long been anticipated, buoyed by new laws allowing 100 percent foreign shareholdings in many equities. But would-be investors are awaiting clarity on which firms can be wholly foreign owned.
SCIC has been instructed to divest from Vinamilk and nine other firms, but at a time of its own choosing.
Dang Quyet Tien, vice head of the finance ministry's financial department for enterprises, said foreign ownership in Vinamilk would not be restricted.
"There's no limit right now," he told Reuters. "But it's up to SCIC how it wants to sell its stake."
Vinamilk closed up 2.56 percent at 120,000 dong at the midday break.