University of Utah officials have acknowledged that a box of backup tapes containing billing records of some 2.2 million patients was stolen early this month from the car of a courier.

The missing tapes were taken on June 2 from the car of an employee of Perpetual Storage, an independent storage company hired by the university to transport its computer tapes to off-site facilities, said school officials. The tapes contained names, demographic information and Social Security numbers of patients of the University of Utah Hospitals & Clinics health care system.

The health care system has suspended all backup tape deliveries to Perpetual Storage pending a full review of the company's protocols and procedures, said a university spokeswoman.

The spokeswoman confirmed that Perpetual Storage fired the individual involved with the data breach for violating company data security transportation protocols. The driver had been employed by Perpetual Storage for 18 years, she said.

The spokeswoman said the driver informed his employer immediately upon discovering that the tapes were lost. Perpetual Storage informed the University of Utah Hospitals & Clinics officials within 24 hours of the breach, she added.

The university spokeswoman declined to say whether any of the missing data storage tapes were encrypted.

Lorris Betz, senior vice-president for Health Sciences and CEO of University of Utah Health & Clinics, said in a posted alert that it was unlikely that any information on the backup tapes will be exposed to thieves.

"Although it is unlikely that information on the tapes will be compromised, we are nevertheless taking aggressive steps to protect our patients' confidentiality," Betz said in the post.

The university plans to mail notification letters to all patients whose data was held on the stolen tapes and offer them free credit monitoring services. The missing tapes did not hold any credit card information, noted school officials.

The university is offering a reward of $1,000 (£500 approx) for the return of the stolen tapes with "no questions asked." The Salt Lake County Sheriff's Department, the FBI and US Postal Service are investigating the theft.