DETROIT (AP) — Michigan State Police has suspended the contract with the company that issues the state’s breath alcohol testing devices amid concerns the results could be flawed.

In a letter written to police and prosecutors statewide, state police officials warned law enforcement agencies about “performance-related issues” with the Datamaster DMT breathalyzer devices, according to The Detroit News. Such issues could affect drunken driving cases.

The letter did not identify the problems or how they were uncovered.

State police Lt. Michael Shaw said a stop order was immediately issued as soon as they “noticed some issues with the vendor that was responsible for maintenance and auditing the DataMasters around the state.”

A phone call to the vendor, Intoximeters Inc., of St. Louis, was not returned Saturday.

“We will be (setting) up a unit in order to assume the responsibilities of that vendor,” Shaw said. “Authorities will keep using the devices, but Michigan State Police, not the vendor, will calibrate them,” Shaw said.

State police will also take over the contractor’s duties of certifying and serving the breathalyzer units.