An unnamed contractor is being blamed for a data breach at Gap Inc. that has compromised the data of about 800,000 people who applied for jobs with the U.S. clothing retailer.

On Friday, Gap said the data had been stored on two laptop computers that were stolen from the vendor's offices. Although the job applicant information on the laptop -- which included Social Security numbers -- was supposed to be encrypted, it was not.

Gap's online job site is run by Taleo, but on Friday, Taleo said that it wasn't responsible for the breach. "The data loss involved a Gap vendor that processes job applicant data. Taleo was not the vendor involved in this data loss," the company said in a statement.

Gap learned of the theft on Sept. 19, the company said in a letter sent to those affected.

Still, "the company has no reason to believe the data contained on the computer was the target of the theft or that the personal information had been accessed or used improperly," Gap said in a statement.

The laptop had information on people who applied for positions at Gap stores, including Banana Republic and Old Navy, between July 2006 and June 2007. Gap has set up a Web site to assist those who may have been affected by the breach. Victims are being offered one year of credit monitoring and fraud resolution assistance.

Information on more than 165 million U.S. residents has been compromised since early 2005, according to Privacy Rights Clearinghouse, a privacy advocacy group.

Many of these breaches have been caused by lost or stolen laptops, as was the case with Gap. However, it is not clear how many of these events actually resulted in identity theft.