The deputy prime minister of Yugoslavia, Vuk Draskovic, has been dismissed.
The authorities said he had made public statements that were contrary to government policy.
But at a news conference, Mr Draskovic denied this, and said he had no idea why he had been dismissed.
He rejected accusations that he supported NATO airstrikes.
Earlier this week Mr Draskovic criticised the government's handling of the Kosovo crisis, and urged President Milosevic to be more honest with the Serbian people.
Mr Draskovic is a former opposition leader, and a BBC correspondent in Belgrade says his departure will remove one of the last remaining voices of moderation from the Belgrade leadership.
Three other members of Mr Draskovic's party have resigned their posts as government ministers.
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