Following revelations that a high-ranking member of Wikipedia's bureaucracy used his cloak of anonymity to lie about being a professor of religion, the free Internet encyclopedia plans to ask contributors who claim such credentials to identify themselves.

Wikipedia founder Jimmy Wales said in interviews by phone and instant message yesterday from Japan that contributors still would be able to remain anonymous. But he said they should only be allowed to cite professional expertise in a subject if those credentials have been verified.

"We always prefer to give a positive incentive rather than absolute prohibition, so that people can contribute without a lot of hassle," Mr. Wales wrote.

He suggested such a plan two years ago, but the idea gained currency after the recent discovery that a prolific Wikipedia contributor who wrote under the pen name "Essjay" and claimed to be a professor of theology turned out to be a 24-year-old college dropout, Ryan Jordan.

Mr. Jordan's fraud came to light last week when The New Yorker published an editor's note stating that a 2006 Wikipedia profile in the magazine had erroneously described Essjay's purported academic resume. The New Yorker said a Wikipedia higher-up had vouched for Essjay to the author of the piece, Stacy Schiff, but that neither knew Essjay's real identity.

In addition to contributing thousands of articles to the sprawling Web encyclopedia, Mr. Jordan recently had been promoted to arbitrator, a position for trusted members of the community.

Arbitrators can overrule an edit made by another volunteer or block people who abuse the site.

Mr. Jordan also was hired in January by Wikia Inc., a for-profit venture run by Mr. Wales. He has since been dismissed.

Mr. Jordan has not returned an e-mail seeking comment, but in a note on his Wikipedia "user page" before it was officially "retired," he apologized for any harm he caused Wikipedia.

"It was, quite honestly, my impression that it was well known that I was not who I claimed to be, and that in the absence of any confirmation, no respectible (sic) publication would print it," he wrote.

Wikipedia is full of anonymous contributors such as Essjay, whose user page also once proclaimed: "My Wikipedia motto is 'Lux et Veritas' (Light and Truth) and I believe more individuals should contribute with an intention to bring light to the community and truth to the encyclopedia."

The anonymity of the site is a frequent cause of mischief and has raised concerns about the credibility of the site.