Japan is urging local authorities and fishermen to be on the alert after several boats thought to be from North Korea were found on its northern coast. Picture: Kantaro Saki/Kyodo News via AP

Tokyo — Japan is stepping up patrols and urging local authorities and fishermen to be on the alert after several boats thought to be from North Korea, some carrying dead bodies, were found on its northern coast.

"The coast guard and police have to cooperate to step up sea patrols around Japan," the chief government spokesperson, Yoshihide Suga, said Tuesday when asked about reports that a boat carrying eight dead bodies was found on the coast of Akita prefecture, which faces North Korea across the Sea of Japan.

"The government intends to improve this to ensure we can guard against suspicious boats or people arriving in Japan," Suga said.

He said local authorities, fishermen and residents should report if they spot any questionable boats or people.

Read: Eight bodies found on boat washed up on Japanese beach

Last week, police rescued eight people thought to be North Korean fishermen who ended up stranded along with their squid catch.

It is unclear if the people aboard the several dozen North Korean boats that drift near Japanese shores each year are intending to defect or simply unable to make their way back aboard their unseaworthy wooden boats.

The boat found Monday appeared to have no flag or other markings and was reported to be "nationality unclear." But the crude vessel with its very low gunwale is similar to other poorly equipped boats often seen operating from North Korea.

The Kyodo News service and other Japanese media reported that eight bodies were found under the boat's decks and taken ashore by stretcher.

Associated Press