European Commission spokeswoman Amelia Torres said the closed-door session with representatives of the 15 EU governments ended around midday.
"The member states have unanimously backed the Commission's draft decision," she said, without elaborating.
The draft ruling could be adopted as early as next week — barring a last-minute settlement.
A Microsoft spokesman in Brussels said earlier that the company's legal team remained in daily contact with the Commission, trying to resolve the long-running case amicably.
Microsoft is seeking to avert a far-reaching order that would not only result in a fine of up to $3 billion, but also force the company to change the way it sells its flagship Windows to computer makers in Europe.
A negative decision would be the biggest setback for Microsoft since a U.S. judge found it guilty of antitrust violations involving Internet browsers in 2000. Microsoft reached a settlement with the Bush administration a year later that allowed it to keep its Internet Explorer in Windows with some conditions.
Sources familiar with the EU case say the draft ruling similarly finds Microsoft abused its monopoly in computer operating software to gain share in markets for digital media players and low-end servers.
The EU wants to force Microsoft to offer computer makers a version of Windows without its own Media Player to give rivals like RealNetworks Inc. a better shot at getting onto consumer desktops. It also would demand Microsoft release more basic code for Windows to improve "interoperability" with competing networking software made by Sun Microsystems and others.
Monday's committee session gave governments a final opportunity to comment on the Commission's draft decision, which was sent to national capitals last month.
The committee reconvenes next Monday to consider the size of the fine against Microsoft, and the Commission is expected to adopt the decision as early as March 24.
Microsoft is expected to ask the European Court of Justice to suspend any negative decision pending appeal, but legal experts say such an injunction is not automatic.
Given the rapidly changing nature of the industry, the Commission is expected to argue its order would be meaningless by the time the appeal is decided, a process that can drag on for years.
By Paul Geitner