The US ambassador to the United Nations has again heavily criticised the UN deputy secretary general for his remarks about US policy on the UN.
Mr Bolton says the US wants to support an effective UN
John Bolton, in an interview with the BBC, said Mark Malloch Brown's comments were a "severe political mistake".
Mr Malloch Brown had said Washington did not stand up for the UN against domestic critics and used the organisation as a diplomatic tool.
Mr Bolton has called on Kofi Annan to repudiate his deputy's speech.
"I think this is... probably the most severe political mistake that any high official of the UN has made in that period," he told the BBC's Newsnight programme.
"The reason it's a mistake is that we are engaged, the United States and many other countries, in a sustained effort to get substantial reform in the UN system, and I fear that Malloch Brown's speech will set those reform efforts back."
In his speech in New York on Tuesday, Mr Malloch Brown said: "Much of the public discourse that reaches the US heartland has been largely abandoned to its loudest detractors, such as Rush Limbaugh and Fox News."
Depending on the UN while tolerating "too much unchecked UN-bashing and stereotyping" was "simply not sustainable", he said.
"You will lose the UN one way or another."
Looming budget crisis
UN officials said the speech was intended as a warning signal about the looming budget crisis.
The organisation could run out of money at the end of June and the US - its biggest paymaster - may withhold its dues unless there is enough progress by the UN on management reform, observers say.
Mr Annan (R) says he will stand by his deputy's remarks
Mr Bolton accused Mr Malloch Brown of employing "a condescending, patronising tone about the American people".
He said he told the secretary general: "I've known you since 1989, and I'm telling you, this is the worst mistake by a senior UN official that I have seen in that entire time."
"Even though the target of the speech was the United States, the victim, I fear, will be the United Nations," he told reporters after speaking with Mr Annan.
A spokesman for the UN chief said he stood by his deputy's remarks, who said he had been appealing for engagement from Americans.
"Engage here, engage consistently and go out and engage with the American public to say the UN matters, and for the life of me, I can't understand how that can be construed as an anti-American speech," Mr Malloch Brown said.