In an unusual rebuke of an ally, President Bush said yesterday that he was concerned that Russian President Vladimir Putin's moves to centralize power could undermine democracy.

Putin's announcement on Monday that he would seek further control over regional governments and the legislative branch has been widely interpreted as an attempt to use the fear of terrorism as a justification for imposing tyranny. Bush's silence for two days led to widespread questions about his commitment to promoting freedom in all parts of the world.

Bush, in remarks at an East Room concert and reception honoring Hispanic Heritage Month, said he is "concerned about the decisions that are being made in Russia that could undermine democracy in Russia."

"Great countries, great democracies have a balance of power between central government and local governments, a balance of power within central governments between the executive branch and the legislative branch and the judicial branch," he said. "As governments fight the enemies of democracy, they must uphold the principles of democracy."

Bush did not repeat the praise of Putin as "a man who I admire" that he offered Sunday when he stopped by the Russian Embassy to write a note in a condolence book for the more than 300 children and adults killed recently in the terrorist siege of a school in southern Russia. Bush began his administration with a warm relationship with Putin, but some presidential aides feel they have gotten little for their overtures and were angry that Putin opposed the invasion of Iraq.

Putin cited the threat of terrorism when he said in televised remarks Monday that he would ask parliament to radically restructure the nation's political system to end the popular election of governors and independent lawmakers.

Although on Tuesday, Secretary of State Colin L. Powell had criticized the effort to concentrate power, Bush's decision to scold Putin before television cameras reflected the White House calculation that he needed to respond directly to Putin's proposals.

Stephen R. Sestanovich, an authority on Russia who is a fellow at the Council on Foreign Relations, said many Russians have worried that Putin has concluded from the White House's public and private statements that Washington had no objection to his efforts to restrict the media and block opposition.

"The approach until now has been to let Colin Powell deliver the bad news," Sestanovich said. "The Russian read of that has been that, as long as the president didn't say too much or too publicly, they didn't have to take it too seriously. So it's good for the president to be more forthright and make it clear that it's not just Colin Powell wringing his hands."

A White House official said Bush aides had seen "misperceptions in the media" about Bush's commitment to a consistent defense of democracy. Administration officials plan to try to soften the criticism by telling their Russian counterparts that Bush intended the comments as "counsel from a friend."

Bush and Putin have not personally discussed the matter, aides said. The last time Bush talked to Putin was on Sept. 1, when he offered condolences and assistance after the siege at the school began.