GENEVA, Dec. 10— Whether governments should support open-source software like Linux over commercial software like Microsoft's Windows was debated on Wednesday at a United Nations conference on closing the so-called digital divide between rich and poor countries.

Samuel Guimarães, executive secretary in the Ministry of Foreign Affairs of Brazil, told government representatives at the opening sessions of the meeting that open-source, or free-to-share, software was crucial for the developing world because it would permit poorer countries to develop their own technology instead of having to import it.

Brazil, with the support of India, South Africa and China, wanted the delegates to the meeting, the World Summit on the Information Society, to endorse open-source software as the best way to bridge the technology gap.

But while language declaring open-source software an important option was in a statement by the delegates, it was watered down considerably after pressure from industrialized countries, some conference participants said.

The information and communications technology arm of the United Nations Development Program is advising governments that want to move to open-source software on how that software could become a foundation for local software development.

But Raoul Zambrano, an adviser to the program, said the office was cautioning nations not to require open source for their governments because the goal should be to create choice and competition.

The program plans to open a regional center in Europe early next year to offer support to countries in the Balkans and on the Baltic Sea on this issue.

Veni Markovski, an adviser to the Bulgarian president on technology, said he had asked the United Nations for help because he thought the Bulgarian government had spent too much money on Microsoft products.

Microsoft denied any overcharging.

Microsoft's influence is so great, Mr. Markovski said, that ''the end user, the citizen, doesn't have a choice and the government doesn't have a choice.''

Microsoft confirmed on Wednesday that it was discussing with the United Nations program how to work together most effectively.

Microsoft, which has said it will invest $1 billion on projects to help bridge the digital divide, said it did not require that its software be used in such projects.

''People, at the end of the day, have the right to choose, and we support that,'' said Claudia Toth, a spokeswoman for Microsoft.

Peter Dravis, a consultant who wrote a report about open-source software for the World Bank, said, ''It is a tough call for a lot of agencies and groups when Microsoft offers to give away software to schools and governments.''

But he said that there was a growing demand for open-source software, and that Microsoft's deals with governments would not ensure market dominance.

Photo: Kofi Annan, the secretary general of the United Nations, sent an e-mail message to a school yesterday during the World Summit on the Information Society, which is sponsored by the United Nations. (Photo by Agence France-Presse -- Getty Images)