Conservative commentator Armstrong Williams pocketed $241,000 (pound;129,000) from the pact, which also called for him to feature US education secretary Rod Paige on his show and promote President Bush’s education reforms to fellow African American journalists.

Mr Williams’s show, The Right Side, was broadcast on local TV stations across America and he was a familiar face on cable news channels CNN and Fox. His column ran in 50 newspapers, including USA Today, which obtained details of the arrangement under a Freedom of Information request.

Mr Williams was under contract “to regularly comment on the No Child Left Behind Act during ... his broadcasts” and use his long-term association with Black Forum, an African American current affairs TV programme, to “encourage the producers to periodically address” the reforms, according to documents.

“Secretary Paige and other officials shall have the option of appearing from time to time as studio guests,” the contract added.

The education department defended the agreement, struck in 2003, as a legitimate way of explaining the reforms to minorities targeted by the legislation, calling it “permissible use of taxpayer funds under legal government contracting procedures”.

But education historian Jeffrey Mirel of Michigan university branded the move “sleazy”, saying it was unprecedented in US education annals. “Why don’t you pay me for this interview and I’ll tell you what you want to hear - it’s unseemly,” he said. “The use of public money to promote a particular education reform in the guise of news or dispassionate commentary is not legitimate.”

Mr Williams was dropped from his column and had his TV show axed last week, following the revelations. In multiple TV appearances, he was contrite, apologising for “bad judgement”, but he drew the line at returning the money.

“That would be ludicrous,” he said. “They bought advertising and they got it.”