PITTSBURGH — A police officer has sued the city and its former mayor claiming she’s been wrongly suspended from her job since early last year because she opposed favors the former mayor allegedly granted to a friend with a valet parking business.

Tonya Montgomery-Ford filed the federal lawsuit Thursday against the city and former Mayor Luke Ravenstahl.

Federal prosecutors have acknowledged an investigation involving the city’s police bureau and Ravenstahl since last year, though the former mayor has not been charged.

Ravenstahl forced his hand-picked police chief, Nathan Harper, to resign as a result of the investigation in February 2013. A year later, Harper was sentenced to 18 months in prison in connection with an illegal police slush fund.

Ford contends she was wrongly suspended without explanation the day after Harper resigned. She seeks reinstatement and unspecified damages in an 11-page complaint that contends she upset Ravenstahl and Assistant Chief George Trosky by opposing valet parking variances for a company owned by their friend, Robert Gigliotti.

Ford had been an assistant to the police chief since 2001, years before Ravenstahl took office in 2006 and then appointed Harper. Part of her job was to process parking variances, which allow companies to use metered city parking spaces for free, the lawsuit said.

Ford contends Gigliotti’s Tri-State Valet allegedly got its variances because of his relationship with Ravenstahl and Trosky. That helped Gigliotti make more money because he didn’t have to pay to park some customers’ cars in commercial garages or lots, the lawsuit said.