Russia and China are urging Iran to cooperate with the International
Atomic Energy Agency on any probe of its newly revealed uranium
In a statement Friday, Russian President Dmitri Medvedev said disclosure of the site is a cause for "serious concern." But he did not raise the threat of sanctions.
A Chinese spokesman says China is following the situation closely.
U.S. President Barack Obama and other Western leaders have insisted the IAEA gain immediate access to the facility to ensure it is not being built to produce atomic weapons.
Russia and China are two of the five permanent members of the United Nations Security Council, but have historically been more reluctant than the United States and European nations to punish Iran for enriching uranium.
The Security Council has passed three sets of sanctions urging Iran to halt uranium enrichment, a process that can be used to make nuclear weapons.
Some information for this report was provided by AFP, AP and Reuters.