No country opposed the Universal Declaration of Human Rights. Every country that was a UN member at the time either voted in favor of it, or abstained because they believed it didn’t go far enough to include denying human rights to nazis and fascists.

Although, the Universal Declaration of Human Rights itself isn’t legally binding. It’s just a joint statement by UN members declaring what is considered human rights. It’s not like a violation of International Laws if they just ignore what they said. (Even if it were an international law, who’s gonna enforce it?)

The Third General Assembly adopted the Declaration just before midnight on December 10, 1948 with a vote of 48 to zero and eight abstentions. The abstentions came from the USSR, the Ukrainian Soviet Socialist Republic (UKSSR), the BSSR, Yugoslavia, Poland, Saudi Arabia and South Africa.

The Six Communist Abstentions

The Communist abstentions coalesced around the view that the Declaration did not go far enough. They had repeatedly made the point that to protect human rights adequately, the Declaration needed explicitly to condemn fascism and Nazism. Since it did not do that, they would abstain from the vote. The deep animosity that exists between Marxist egalitarianism and Nazi racism led the USSR delegation to propose amendments to what became Articles 19 and 20 stating that fascists and Nazis did not have human rights to freedom of expression and association. When those amendments were rejected, the Communists, rather than abstaining, which was their custom, voted against these articles.

https://ccnmtl.columbia.edu/projects/mmt/udhr/udhr_general/drafting_history_10.html