The U.S. Department of Labor has sued the Fifth Third Bancorp of Ohio for mismanaging $20 million in union pension fund invested in a Detroit property development project.

The department announced on Thursday that the lawsuit it filed on Dec. 28 with the U.S. District Court in Detroit seeks to recover the money and interests of the Operating Engineers Local 324 Pension Fund based in Troy, Michigan.

According to the lawsuit, the bank acted as the pension fund's investment manager and fiduciary from Aug. 25, 2003, to Oct. 1, 2006 with Carey Milestone Advisors as the investment advisor.

Fifth Third invested $23 million to develop a property located at 1001 Woodward bought by the pension fund in 1999. In 2004, the bank changed its development strategy and sold the property to the Cavaliere Group for only $4.5 million. That year, the investment to the property had reached $28 million.

Detnews.com quoted Fifth Third bank spokeswoman Debra DeCourcy as saying that the case is without merit. She did not comment further as the case is under litigation.