The Maryland state prosecutor has launched a criminal investigation into whether Montgomery County officials improperly used county resources during two ongoing referendum campaigns.

The ballot measures involve a local police labor law and a county hiring authority for people with severe disabilities. The county has created Web sites for the two initiatives. It also has put ads on its Ride On buses and distributed fliers about the police referendum.

“This Office will be conducting an investigation into these activities to determine whether any criminal violations warranting criminal prosecution have been committed in connection with these activities,” State Prosecutor Emmet C. Davitt wrote to the county.

He said the county could be fined $25,000 and county employees could be imprisoned for up to a year for violating election law.

In response, Marc Hansen, the county’s top attorney, wrote that the county acted appropriately and had sought advice from state elections officials for similar political activity two years ago.

“I am disappointed that you would threaten to prosecute unidentified County employees and officials,” Hansen wrote. “These individuals have done nothing more than give voice to the County’s official position.”

Davitt started the investigation after receiving a request from the county’s Fraternal Order of Police Lodge 35, which is fighting to repeal a law that it says unfairly limits its ability to bargain for certain rights. Through his office, Davitt declined to comment Tuesday.

The county police labor law, approved by the county council last year, would remove a method of bargaining that the FOP has had for three decades. The union successfully put the law to a referendum in August.

The other referendum, spearheaded by Council member Phil Andrews (D-Gaithersburg-Rockville), would create a county hiring authority that would promote and hire people with severe disabilities in county jobs.

Also on Tuesday, the American Civil Liberties Union of Maryland issued a statement saying the FOP was not allowed to run ads on county buses that urge voters to strike down the law, though the county could run its ads supporting the law.

County spokesman Patrick Lacefield denied that the county censored political speech. He said County Executive Isiah Leggett (D) had decided to make an exception for the FOP’s ads, and that the union would be able to purchase them soon.

Union officials and the ACLU said Tuesday that they had not been told by the county that they would be able to run the ads.