A State Department expert on weapons testified before congressional committees last week that the Bush Administration pressured him to distort some evidence in his analysis of the Iraq situation.

A top State Department expert on chemical and biological weapons told Congressional committees in closed-door hearings last week that he had been pressed to tailor his analysis on Iraq and other matters to conform with the Bush administration's views, several Congressional officials said today.

The officials described what they said was a dramatic moment at a House Intelligence Committee hearing last week when the weapons expert came forward to tell Congress he had felt such pressure. By speaking out, they said, the senior intelligence expert, identified by several officials as Christian Westermann, became the first member of the intelligence community on active service to make this sort of admission to members of Congress.