DULUTH, Minn. (AP) - An oceangoing bulk freighter is being held outside Duluth while the U.S. Coast Guard investigates potential environmental law violations.

The Cornelia is a 16,800-ton German "saltie" home-ported in Monrovia. The ship has been held there since Nov. 5 after loading a cargo of grain in Superior, Wisconsin.

Coast Guard Chief Petty Officer Lauren Jorgensen said Tuesday the ship and crew are prohibited from leaving port until given clearance by U.S. Customs.

Jorgensen tells reporters the Coast Guard is investigating the vessel for alleged violations of U.S. environmental regulations.

Jorgensen says the ship poses no public safety threat. No individuals have been detained as part of the investigation.

The Cornelia is owned by Mineralien Schiffahrt, a German dry bulk cargo shipper. The ship flies the Liberian flag.