Jollibee declined to comment. Highlands Coffee did not respond to Reuters 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.
Jollibee has been rapidly expanding overseas and especially across Southeast Asia, aiming to capture growing consumer spending in the region of some 680 million people.
Jollibee operates the largest food service network in the Philippines with more than 1,500 stores in 17 countries, including U.S. brand Coffee Bean & Tea Leaf and its own fast-food chain with the ubiquitous smiling bee logo.
