Three workers from Chrysler Group LLC's Jefferson North plant were arrested recently for alleged drug use during their lunch break after police were tipped off by the automaker.

The workers were arrested on Jan. 24 but have not been formally charged, said Det. Lt. Robert Honey, of the Michigan State Police's County of Macomb Enforcement Team.

The arrests mark the second publicized instance of apparent drug use at the Detroit assembly plant in six months. Last fall, FOX 2 TV captured video of workers from the same plant drinking and smoking what appeared to be drugs during their lunch break. Chrysler fired 13 workers as a result of that incident.

Police said Chrysler contacted them last month after the Auburn Hills automaker received a tip about more alleged drug use at the plant, which employs 2,600 workers and produces the Jeep Grand Cherokee and Dodge Durango sport utility vehicles.

"Our office did surveillance on them and observed them go to a house in Detroit," Lt. Honey said. The workers may not be identified because they haven't been arraigned, he said.