Jollibee declined to comment. Highlands Coffee did not respond to requests seeking comment on Tuesday. Jollibee initially bought a small stake in Highlands Coffee a decade ago and then took a controlling interest. Highlands Coffee, which was established in 1999, began as a coffee products packager in Hanoi and has since grown to become a chain with more than 500 stores in Vietnam and the Philippines. The sources said the stake sale, if successful, could eventually pave the way for an IPO of Highlands Coffee, a move that Jollibee has been considering since many years. Vietnam, with a population of 99 million, is Asia's fastest growing economy with gross domestic product seen expanding 8% this year and 6.5% next year, the government said last month. A boom in coffee drinking has spawned big domestic brands in Southeast Asia. Last year, Indonesian coffee chain Kopi Kenangan was valued at more than $1 billion in a funding exercise.