A Japanese trawler from the northern prefecture of Hokkaido is believed to have been taken to Russia by the country's border guards.
Officials at a fishery cooperative in the city of Wakkanai say the Number 172 Eihomaru, with a crew of more than 10, was inspected by Russian authorities off the city on Friday morning.
The cooperative, to which the boat belongs, was informed by another ship operating nearby that the Eihomaru appeared to have been taken away by the Russian guards.
The Eihomaru was reportedly operating about 80 kilometers east of Wakkanai's Cape Soya.
Officials at the Russian Consulate in the city of Sapporo told NHK that they received a report earlier in the day that a Japanese fishing boat had been inspected by Russian authorities off Wakkanai.