Transportation Secretary Anthony Foxx was paid nearly a half-million dollars by a bus company while mayor of Charlotte, North Carolina, even though he performed no work for the company, according to a lawsuit filed in U.S. Bankruptcy Court.

The lawsuit was filed in North Carolina by Elaine Rudisill, a trustee for the bankrupt bus company, DesignLine USA. The suit seeks the return of $421,000 that Foxx was paid over four years as the company's deputy general counsel.

The company's records do not reflect any work performed by Foxx, according to the lawsuit.

The suit alleges that there was no general counsel for the company, and no evidence that Foxx was in contact with outside lawyers employed by the company. It charges that Foxx spent little or no time at the company's offices.

Foxx resigned from the company on July 1, 2013, the day before he became transportation secretary, the lawsuit says.

"This is a routine adversary claim that is one of dozens and dozens that have been brought at the last minute as the statute of limitations is about run (out)," said Mark MacDougall, a lawyer for Foxx. "We are very confident this will be resolved in Secretary Foxx's favor."

He noted that Foxx was an employee of the company, but not a director, officer or shareholder. During his tenure as mayor, Foxx recused himself from voting on the city council on issues involving DesignLine due to the potential for a conflict of interest.

DesignLine made hybrid-electric shuttle buses bought by the Charlotte Douglas International Airport, which the city owns. Foxx was the mayor from 2009 to 2013 and employed by DesignLine for roughly the same period.

DesignLine filed for bankruptcy in 2013. The shuttle buses were purchased by the airport in 2007, but sold off in 2014 because they were plagued by maintenance problems, according to The Charlotte Observer.

DesignLine was moved from New Zealand to Charlotte after a group of investors led by retired Air Force Lt. Gen. Buster Glosson and his son, Brad, bought the company in 2006, the newspaper reported. DesignLine attracted politically connected investors such as former North Carolina Gov. Jim Martin.