WASHINGTON — Prime Minister Brown of Britain flew into America last night for his first meeting with President Bush amid reports that he could withdraw British troops from Iraq earlier than expected.

As he left Britain, the prime minister spoke of strengthening the “special relationship” but, crucially, was silent on Iraq.

There is growing concern in Washington following a visit by Simon McDonald, Mr. Brown’s chief foreign policy adviser, in which he reportedly asked what the implications would be if Britain pulled its troops out of Basra and southern Iraq.

Mr. Brown’s first prime ministerial visit to the US will last less than 24 hours.

His spokesman insisted yesterday that there was no significance in Mr. Brown’s failure to mention Iraq in his pre-Camp David statement.

He added that Mr. McDonald had made clear during his talks in Washington that Britain’s Iraq policy had not changed.

In his statement yesterday, the prime minister insisted he had always been an “Atlanticist and a great admirer of the American spirit, enterprise, and national purpose.”

He said, “Winston Churchill spoke of what he called ‘the joint inheritance’ of our two countries. But he did not mean just our shared historical experiences, but a belief in what he called ‘the great principles of freedom and the rights of man.'”

But American officials are keen to look beyond the Churchillian references to discover exactly how Mr. Brown, a frequent visitor to American but an unknown quantity at the White House, views what Churchill himself called the “special relationship.”