"It's just, you know, more despicable comments from a terrorist," State Department spokesman Sean McCormack told reporters when asked to comment on the remarks.

"And if anybody needed ... more of a contrast between what ... the West and the United States stand for, in terms of democracy and what these terrorists stand for, I don't think you need to go any further than those comments," he said.

In an Internet audio-message, Zawahiri insulted Obama and other black Americans who have held high office in the US administration with the term used by the late black militant leader Malcolm X.

"It is true about you and people like you ... what alcolm X said about the house negroes," he said, naming former secretary of state Colin Powell and the current ecretary, Condoleezza Rice.

An English transcript of the speech purportedly by he Al-Qaeda number two was provided by Al-Qaeda's media arm As-Sahab.

The tape features an old speech by Malcolm X in hich he used the two terms, referring to house slaves who were considered more docile and on better terms with their asters than the field slaves.