By Gary Robertson

RICHMOND, Va. (Reuters) - The costs to the University of Virginia after a discredited report by Rolling Stone magazine of a fraternity gang rape are mounting, with lawyers' contracts totaling more than $500,000, a newspaper reported on Sunday.

Virginia's flagship university was thrown into turmoil in November after Rolling Stone reported about a 2012 gang rape in a fraternity. The magazine stepped away from its story in December, citing discrepancies in the alleged victim's account.

To tighten security on the Charlottesville campus, the university’s Board of Visitors, or trustees, were told in December that one-time infrastructure improvements, such as upgraded camera and lighting systems, would cost an estimated $3.5 million.

Estimated operating costs in fiscal years 2014-15, which could include more counselors, training and security personnel, would add another $1.4 million.

As for legal expenses, the Daily-Progress newspaper in Charlottesville on Sunday published a contract totaling $500,000 for the international law firm of O'Melveny & Myers.

The Virginia attorney general's office has named the firm an independent counsel to investigate how the university handled the 2012 report of sexual violence reported in Rolling Stone, Michael Kelly, a spokesman for the attorney general’s office, said on Sunday.

Kelly said the bills from the law firm would be reviewed by the attorney general’s office and then forwarded to the Board of Visitors for payment.

A second law firm, Pepper Hamilton of Philadelphia, will assist the university with its “response to and handling of sexual and gender-based harassment and violence complaints,” according to its contract published in the Daily-Progress.

The disclosure of more costs to the university comes after its fraternities and sororities signed agreements designed to prevent sexual assaults and binge drinking.

Legislation also has been introduced in the Virginia General Assembly requiring notification of prosecutors within 48 hours after a victim reports a sexual assault to campus or local law enforcement authorities.

(Editing by Ian Simpson and Eric Walsh)