UNITED NATIONS (AP) – The United Nations’ No. 2 official accused the U.S. government of keeping Middle America in the dark about the world body’s good works, a rare direct criticism that drew an angry response Wednesday from Ambassador John Bolton.

Bolton called Tuesday’s speech by Deputy Secretary-General Mark Malloch Brown a “very, very grave mistake” that could undermine Secretary-General Kofi Annan’s efforts to push through an ambitious agenda at the world body.

“I spoke to the secretary-general this morning, I said ‘I’ve known you since 1989 and I’m telling you this is the worst mistake by a senior U.N. official that I have seen in that entire time,'” Bolton told reporters on Wednesday.

“To have the deputy secretary-general criticize the United States in such a manner can only do grave harm to the United Nations,” Bolton said.

In the speech, Malloch Brown said the United States relies on the United Nations as a diplomatic tool but doesn’t defend it against criticism at home, a policy of “stealth diplomacy” that he called unsustainable.

He lamented that the good works of the U.N. are largely lost because “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.”

“The U.N.’s role is in effect a secret in Middle America even as it is highlighted in the Middle East and other parts of the world,” Malloch Brown said.

The speech was delivered at a daylong conference sponsored by two think tanks, the Center for American Progress and The Century Foundation. Malloch Brown called it a “sincere and constructive critique of U.S. policy toward the U.N. by a friend and admirer.”

It was a rare instance of a senior U.N. official directly and openly criticizing a member state. An unwritten U.N. rule says high-ranking officials don’t name names or shame nations.

Yet Malloch Brown and even Annan have done so in the past. Last year, with the U.N. under intense criticism over the Iraq oil for food program, Annan said opponents of the U.N. had been “relentless,” and the world body wasn’t fighting back enough.

U.S. officials, including Bolton, said they were especially upset that Malloch Brown, a Briton, mentioned “Middle America.”

Bolton said Malloch Brown’s “condescending, patronizing tone about the American people” was the worst part about the speech.

“Fundamentally and very sadly, this was a criticism of the American people, not the American government, by an international civil servant,” Bolton said. “It’s just illegitimate.”

The United Nations had no immediate comment about Bolton’s remarks or whether Annan would respond.

Malloch Brown used the speech to defend U.N. peacekeeping missions in 18 places round the globe. He criticized the United States for voting against the creation of a new Human Rights Council. It was joined by just three nations, with 170 countries voting for the body.

He acknowledged that the U.N. was in desperate need of an overhaul _ in the Security Council, over its budget, and even the headquarters building itself, which hasn’t been renovated for decades.

But the U.S. tendency to criticize the United Nations and to take “maximalist positions,” rather than seeking the middle ground, has made other nations suspicious of its intentions.

Bolton warned that Malloch Brown’s comments could undermine the reforms that Annan wants and that the United States supports.

“To have the deputy secretary-general criticize the United States in such a manner can only do grave harm to the United Nations,” Bolton said. “Even though the target of the speech was the United States, the victim, I fear, will be the United Nations.”