North Korea said Sunday that Japanese rightwing groups committed a grave provocation by swarming Niigata port when the Mangyongbong-92 docked there Thursday.
The Rodong Sinmun, the mouthpiece of the North's ruling Workers Party of Korea, called on the Japanese government to punish those responsible and prevent a recurrence, according to a report by the North's Korean Central News Agency.
The paper described the incident as a "very serious provocation in the history of DPRK-Japan relations."
It claimed that the "incident" was committed at the "tacit connivance of the Japanese authorities."
"The recent incident brought into bolder relief the Japanese reactionaries' vicious and sinister aim to deliberately and systematically foster rowdyism of rightwing gangsters under the pretext of 'people's sentiment'," it said.