The revelation caps a year of disclosures about partisan payments to seemingly independent writers, including Armstrong Williams, the conservative columnist and television host, who received payments from the federal Education Department at a time when he was promoting the Bush administration's education policies in his columns. The administration has been under mounting pressure to become more transparent in its communications after accounts that it paid for and printed articles in Iraqi periodicals as part of its overseas propaganda effort.

Mr. Bandow did not take government money, but the source of his payments -- around $2,000 an article -- is no less controversial. His sometime sponsor, Mr. Abramoff, is at the center of a far-reaching criminal corruption investigation involving several members of Congress, with prosecutors examining whether he sought to bribe lawmakers in exchange for legislative help.

A second scholar, Peter Ferrara, of the Institute for Policy Innovation, acknowledged in the same BusinessWeek Online piece that he had also taken money from Mr. Abramoff in exchange for writing certain opinion articles. But Mr. Ferrara did not apologize for doing so. "I do that all the time," Mr. Ferrara was quoted as saying. He did not reply to an e-mail message seeking comment on Friday.

At Cato and similar institutions, adjunct scholars are not always prohibited from accepting outside consulting roles. But at Cato, said Mr. Dettmer, and at the American Enterprise Institute, said a spokeswoman there, rules require scholars to make public all their affiliations, and there is an expectation that scholars will not embarrass the institution.

"Our scholarship is not for sale," Mr. Dettmer said.

Glenda Winders, the vice president and editor of the Copley News Service, said in a statement that the company was immediately suspending Mr. Bandow's column pending further review.