A 10-meter whale that appears to be weak and having difficulty moving has been spotted near the mouth of Tokyo Bay, prompting a patrol boat to monitor it and alert nearby vessels, the Japan Coast Guard said Thursday.

The whale, whose species has not yet been identified, was discovered at around 11 a.m. Wednesday about 7 km southeast of the Miura Peninsula in Kanagawa Prefecture. It had floated to a point about 17 km south of the peninsula by Thursday morning, the coast guard said.

The whale is drifting away from the bay in a southwesterly direction, the coast guard said.