U.N. Secretary-General Kofi Annan defended his top deputy Thursday from sharp U.S. criticism about a speech that faulted Washington's attitude toward the United Nations.

Serbian President Boris Tadic, left, shakes hands with United Nations Secretary-General Kofi Annan, at U.N. headquarters in New York, Thursday, June 8, 2006. [AP]

Annan told reporters the thrust of the speech from Deputy Secretary-General Mark Malloch Brown was that the United States and the United Nations need each other. He also warned the U.S. against abandoning efforts to reform the world body because of the remarks.

"If one is going to use the argument that 'I'm not satisfied with reform and I'm going to close down the shop,' they will have lots of explanation to do, not just in this building but to the people out there," Annan said.

Malloch Brown's speech to a conference on Tuesday was a rare direct rebuke of the top financial contributor to the U.N. He said the United States relies on the U.N. diplomatically but refuses to defend it before its critics at home.

"Much of the public discourse that reaches the U.S. heartland has been largely abandoned to its loudest detractors such as Rush Limbaugh and Fox News," Malloch Brown said.

The next day, Bolton called the speech a "very, very grave mistake." In remarks that were unusually strong even for the outspoken diplomat, Bolton ominously warned that the speech threatened the organization itself.

In a speech in London on Thursday, Bolton repeated his belief that Malloch Brown's comment could wreak havoc on efforts to reform the U.N. He called the remarks a "classic political mistake and I don't think we've seen the end of the consequences."

The back and forth highlighted the often tense relationship between the United States and the U.N., which was seriously strained after the U.N. Security Council refused to back the Iraq war in 2003.

The relationship has been further strained since the arrival last year of Bolton, a blunt advocate for U.S. interests who has a penchant for eschewing diplomatic language and speaking plainly about his belief that the United Nations desperately needs reform.

That has sometimes alienated other U.N. ambassadors and some U.N. officials, who have said they do not help the reform effort. In an interview with USA Today, Malloch Brown himself said Bolton was "a real force here, but in a way that provokes a lot of reaction and opposition from others."

That tension has been made clear as member states wrestle with proposals to overhaul the way the U.N. is run by giving him more power to make financial decisions and hire and fire staff.

Rich nations including the United States back those reforms, while developing nations that only pay a tiny portion of the U.N. budget are opposed.

Those concerns are particularly pressing because member states imposed a budget cap at the U.N. that expires at the end of June and can only be lifted if they see progress on reform.

Annan told reporters he believed that member states would work out their differences over the budget cap.

"Quite frankly I think we are all too excited and nervous about this budget issue," he said. "I do not see a major budget crisis at the end of this month."

In Washington, State Department spokesman Sean McCormack said Secretary of State Condoleezza Rice expressed her disappointment over Malloch Brown's remarks in a phone conversation with Annan on Wednesday.

McCormack said the United States stands by Bolton's remarks about Malloch Brown's speech.

Yet he also sounded a note of reconciliation, saying that the United States and the United Nations "do a lot of good work together around the world."

"We're a leading supporter of the World Health Organization, which is fighting HIV/ AIDS around the world as well as the threat of avian influenza," McCormack said.