Microsoft has stopped offering its Windows Live Messenger service to users in five countries that are subject to US sanctions.

People in Cuba, Syria, Iran, Sudan and North Korea no longer have access to Microsoft's free, web-based instant-messaging service, Microsoft said.

The US considers each of those countries to be hostile or threatening in some way to its national interests. Details of the trade and economic sanctions against them can be viewed at the U.S. Office of Foreign Assets Control.

Microsoft wouldn't comment on why it chose to shut down the service at this time, or how long people in those countries had been able to access Windows Live Messenger. Microsoft said it does not currently do business with those countries.

The LiveSide.net blog first reported Microsoft's ending its IM service in those countries earlier this week.