Microsoft CEO Steve Ballmer will continue talks with European competition commissioner Mario Monti on the antitrust case against the company.

Discussions between Ballmer and Monti ended early Tuesday evening and are expected to resume this morning, a source said.

"There's been a meeting today. Discussions are ongoing. That's all I'll say," Monti's spokeswoman, Amelia Torres, told reporters. Microsoft reiterated that settlement talks continue.

Ballmer's involvement has sparked speculation that Microsoft is about to make its final effort to settle the five-year-long antitrust case. "It indicates that the issues have narrowed sufficiently to bring in the principal characters," one person said on condition of anonymity.

The Commission's draft ruling remains secret. However, people close to both Microsoft and the European Commission said the Commission found Microsoft guilty of abusing the dominant position of its Windows operating system by using it to muscle out rivals in related markets for media-playing software and software that runs servers. The ruling calls for Microsoft to offer PC manufacturers a version of Windows without Media Player, the video and audio playing software, those people said.

In addition imposing a fine, the European competition regulator is likely to demand that Microsoft reveal all the secret code in Windows needed by rivals to make software that interoperates properly with the near-ubiquitous operating system.

If no settlement is reached, the Commission is expected to make its negative ruling on March 24.

Microsoft announced yesterday that Ballmer won't deliver his keynote presentation set for Wednesday at the Microsoft Management Summit in Las Vegas. His appearance was cancelled due to an unforeseen schedule change, the company said. Kirill Tatarinov, corporate vice president of Microsoft's enterprise management division, will cover for Ballmer, according to Microsoft.

Joris Evers in Las Vegas contributed to this report.