News reports citing sources familiar with the case say the European Union is ready to fine Microsoft at least $380 million for allegedly violating antitrust laws.
The European Commission - the union's executive body - says the U.S. computer giant has failed to fully disclose technical information on how its flagship Windows operating system works.
The union ruled in 2004 that Microsoft must make that information known so other companies can design software compatible with Windows.
Microsoft denies violating EU laws.
The sources say the EU is giving Microsoft until the end of the month to comply, or say the company will face the fines. Some information for this report was provided by Bloomberg and Reuters.