The head of the world's chemical weapons regulatory body, Jose Bustani, was dismissed yesterday by a United States-led vote.
Britain was one of the 48 states backing his dismissal, which was opposed by only seven members. There were 43 abstentions.
The vote at the meeting in the Hague of the Organisation for the Prohibition of Chemical Weapons needed a two-thirds majority.
Mr Bustani, a Brazilian diplomat, stormed out of the conference hall, threw his hands in the air and said the vote lacked a legal basis.
Beforehand he said: "The convention does not allow for such a dismissal."
The US state department has accused him of threatening to inspect five unspecified countries "for political ends".
In its statement it said he had a "habit of refusing to consult" members, as when he proposed anti-terrorism measures after the September 11 attacks without first approaching the US.
His opponents accuse him of mismanagement, but the US was booed at the meeting when it failed to produce documentary evidence.
US officials were reported yesterday as saying that in his attempts to persuade Iraq to join the OPCW, Mr Bustani would not take a sufficiently tough stand with Baghdad on chemical weapons inspections.
There has been speculation that the US attitude is dictated by its concern that Mr Bustani's proposals would prevent Washington having a free hand over Iraq.
It was reported last week that hawks in Washington had asked the CIA to investigate Hans Blix, the United Nations chief weapons inspector, in an attempt to undermine him.