Tokyo: Seven crew from Japan and Indonesia were missing on Sunday after a Japanese tuna fishing boat caught fire in the Pacific, local media reported.

A coastguard plane spotted the No. 8 Kaisei-maru emitting orange flames and thick black smoke some 400 kilometres south of Kochi prefecture, national broadcaster NHK said.

The fate of the two Japanese and five Indonesians on board remained unknown. It was also unclear what caused the blaze.

The coastguard received a report from a local fisheries radio station shortly after 6:00 am that it could not contact the 19-tonne vessel.

More than four hours later, its plane found the burning ship, NHK said, showing footage of the vessel with its bridge in flames.

The ship left the port of Kochi on February 20 and planned to reach another port in nearby Wakayama prefecture on Tuesday, Jiji Press said.