"We have taken the decision to carry out a strategic review of our Asian assets, which could lead to a full or partial divestment of our business in the region," chief executive Mikael Granhe said in a statement.
Millicom has a 58.4 percent own subsidiary in Cambodia, a 74.1 percent unit in Laos and 100 percent owned one in Sri Lanka.
Millicom said it had been given a 3G (third generation) license in Sri Lanka.
It 2008, the firm had built 300 new sites, bringing the total to 940.
In the year to March 2009, Millicom said its Sri Lanka subscribers grew 54 percent to 2,111,295. In December the celco had 2,000,071 subscribers.
In the March quarter total subscribers in Asia were at 4,538,357. Millicom says it has a policy of reporting only subscribers who have generated revenues within 60 days and in the case of n