A "significant number" of FBI employees cheated on an exam, the Justice Department acknowledged Monday.

FBI Director Robert Mueller acknowledged in a statement posted on the FBI website on Monday that the cheating may be more widespread that the four field offices under investigation.

Jeff Stein, who writes the SpyTalk blog for the Washington Post, initially reported the acknowledgement.

To ensure that employees understood the importance of its Domestic Investigations and Operations Guide (DIOG), the FBI mandated 16.5 hours of live classroom training and an open-book test for employees involved in operations. Virtually every special agent and intelligence analyst attended the mandatory training within the first several months of the DIOG's December 2008 release.

According to the Justice Department report on the incident, several cheating violations occurred. Here's an excerpt from the report:

Some consulted with others while taking the exam when that was specifically forbidden by the test-taking protocols. Others used or distributed answers sheets or study guides that essentially provided the answers to the test. A few exploited a programming flaw to reveal the answers to the exam. Several supervisors, including two ASACs, two SSAs, and a legal advisor, were involved in such cheating. Almost all of those who cheated falsely certified on Question 51 (the final question of the exam) that they had not consulted with others.

Read the full story at WashingtonPost.com.