The Japanese Coast Guard on Monday said the eight corpses found in a boat drifting near the coast of Akita prefecture might be of North Korean fishermen.
The boat was spotted for the first time on November 24 close to the shore, but due to strong waves, the rescue personnel could reach it only on Sunday, a Coast Guard spokesman told Efe news.
He added that the authorities were trying to determine the sex of the bodies, which were found in a highly decomposed state.
In a separate incident over the weekend, the Japanese Coast Guard recovered two bodies from different parts of the island of Sado in Niigata prefecture, as well as the remains of a boat, the spokesperson added.
Boxes of North Korean tobacco were found close to the bodies, along with life jackets with phrases written in Hangul, the Korean script.
On November 23, a group of eight fishermen, claiming to be from North Korea had reached Yurihonjo, also in Akita prefecture, claiming to have lost their way owing to an engine failure.
Dozens of North Korean boats with fishermen, often dead, are recovered along Japanese coasts every year, the spokesman added.
These boats, known as ghost boats locally, drift away mid-fishing owing to adverse weather conditions, lack of radar equipment, shortage of fuel or engine problems.