One of the top Internet career sites, Monster.com, acknowledging that some of its users are being targeted for identity theft via false job postings, has issued a warning to millions of its registered users.

The TMP Worldwide subsidiary sent e-mails to job-seekers warning them about the possibility of attempts to steal personal information from fake employer job listings.

The e-mail, called a "critical service message," reportedly says that "regrettably, from time to time, false job postings are listed online and used to illegally collect personal information from unsuspecting job seekers."

Monster.com and competitors like CareerBuilder.com and HotJobs.com already post some information cautioning users of the risk of theft of personal information, warning them not to give out Social Security numbers, bank account data and other personal information.

Monster's own privacy policy is stated here. Its FAQ warns that "Monster's Terms of Use prohibit job postings which require job seekers to pay any funds prior to employment. Do not give your credit card numbers (or) bank account number to any prospective employer or engage in any transaction in which you are requested to transfer or exchange currency or funds to or for a prospective employer. Be cautious providing any personal information over the phone or online to prospective employers other than the information you have already provided in your resume.

"Any problems resulting from fraudulent job postings are extremely rare on our site," Monster.com spokesman Kevin Mullins told internetnews.com. "He said the warning was made because "we want to be out front of any potential problems."

Mullins said that the company has dedicated employees "who screen job postings to check for legitimacy." He said he's unaware of any law enforcement or Federal Trade Commission investigations regarding identity theft on the site.

Anyone who is a victim of identity theft can get general Federal Trade Commission information here or may make a formal complaint at this FTC Web site .

The FTC also has installed a toll-free number, 1-877-IDTHEFT (877-438-4338) where consumers who have been victims of identity theft can report the crime and get advice from telephone counselors trained to provide assistance to ID theft victims.