A Japanese patrol ship ran aground off Niigata Prefecture on Wednesday morning and became unable to sail, the coast guard said, adding that no crew members were injured but spilled oil was observed in the area.

While the coast guard is investigating the cause of the incident, which occurred around 6:30 a.m. off Kashiwazaki, its local office said there may have been a human error in the maneuvering of the 3,100-ton Echigo.

Yusuke Ono, head of the Niigata Coast Guard Office, told a press conference that the accident occurred when the 105-meter-long ship was approaching a lighthouse to check that its lighting system was working properly.

Sea water came into some parts of the hull, but there was no concern that the vessel may sink, it said. Weather conditions were rainy with a wind speed of nearly 40 kilometers per hour at the time of the incident.

Japan Coast Guard Commandant Shohei Ishii offered an apology, saying, "It's regrettable that a patrol ship caused an accident even though it was supposed to ensure safety in the sea."

A similar grounding accident involving a Maritime Self-Defense Force vessel off Yamaguchi Prefecture made headlines last week.

Photo taken from a Kyodo News airplane on Jan. 18, 2023, shows the Niigata Coast Guard Office patrol boat Echigo off Kashiwazaki in Niigata Prefecture, northwest of Tokyo. The 3,100-ton vessel was leaking oil after running aground during a patrol. (Kyodo) ==Kyodo
Photo taken on Jan. 18, 2023, shows the Niigata Coast Guard Office patrol boat Echigo off Kashiwazaki in Niigata Prefecture, northwest of Tokyo. The 3,100-ton vessel was leaking oil after running aground during a patrol. (Kyodo) ==Kyodo