A Panamanian-flagged freighter ran aground and split in two in northwestern Japan, and its crew was rescued, the Japanese coast guard said Thursday.

Aerial images show the stern of the " Crimson Polaris " detached and sinking while the other part of the ship remains afloat albeit slightly heeled.

"The Crimson Polaris ran aground off the port of Hachinohe," to the northeast, said a coast guard spokesman, who did not want to be named.

Three patrol boats and three planes were mobilized after it ran aground on Wednesday.

"The 21 crew members, Chinese and Filipinos, were rescued," the spokesman said, adding that the oil from the ship spilled at a distance of about 24 kilometers, without the environmental impact being known at the moment.

Authorities tried to contain the oil spill, but failed to deploy the barrier around the ship, he said.

"The patrol boats will work at night" to avoid collisions, the spokesperson said, adding that no other vessels were known to be involved in the accident.

SOURCE: AFP