A critic of an online encyclopedia written and edited by its users has identified dozens of biographical articles that appear to contain passages lifted from other sites, prompting its administrators to delete several pending a review.

Daniel Brandt found the examples of suspected plagiarism at Wikipedia using a program he created to run a few sentences from about 12,000 articles against Google's search engine. He removed matches in which another site appeared to be copying from Wikipedia, rather than the other way around, and examples in which material is in the public domain and was properly attributed.

Brandt ended with a list of 142 articles, which he brought to Wikipedia's attention.

The site's founder, Jimmy Wales, acknowledged that plagiarized passages do occasionally slip in but he dismissed Brandt's findings as exaggerated.

Wikipedia allows anyone to post, edit and even delete items regardless of expertise and leaves it to other users to catch factual errors and other problems, including plagiarism.

Although plagiarism and copyright infringement are common among sites with user-generated content, Brandt said Wikipedia must be held to a higher standard, a point with which Wales agreed.

''They present it as an encyclopedia,'' Brandt said Friday. ''They go around claiming it's almost as good as Britannica. They are trying to be mainstream respectable.''

Brandt, who has long sparred with Wikipedia over an unflattering biography of himself, called on Wikipedia to conduct a throughout review of all its articles. The site currently has nearly 1.5 million in the English language alone.

Wales said plagiarism is always possible in a site that offers ''wide-open editing ... but in general we take a very strong anti-plagiarism stance.'' Any time plagiarism is brought to the site's attention, he said, Wikipedia administrators review all postings made by that author.

Wikipedia editors have been reviewing the 142 articles in question and have declared a handful to be OK because copied passages came from the public domain. Editors found others where Wikipedia appeared to be the one plagiarized.

But editors found extensive problems in several cases, with many still not yet fully checked.

Articles with offending passages have been stripped of most text. An entire paragraph in Alonzo Clark's entry, for instance, was deleted, leaving the article with the bare-bones: ''Alonzo M. Clark (August 13, 1868-October 12, 1952) was an American politician who was Governor of Wyoming from 1931 to 1933.''

The original article, Brandt said, was copied from a biography on the Wyoming state government site.