Tokyo, 04 Rabi'II,1437 AH, 14 January,2016 , SPA -- A magnitude 6.7 earthquake struck just off Japan's northernmost main island of Hokkaido on Thursday, Reuters quoted Japan's Meteorological Agency, Reuters reported. No tsunami warning was issued and NHK national television said that while there might be some changes in sea level, no tsunami damage was expected. There were no immediate reports of damage. No irregularities were reported at Hokkaido Electric Power's Tomari nuclear plant and Tohoku Electric Power's Higashidori nuclear plant in northern Japan, both of which have been kept shut pending stringent safety checks following the Fukushima disaster, spokesmen at both firms said. There were also no irregularities at the Rokkasho plutonium preprocessing and other nuclear-related facilities in Aomori prefecture, operated by Japan Nuclear Fuel Ltd, the Nuclear Regulation Authority said. -- SPA 10:35 LOCAL TIME 07:35 GMT www.spa.gov.sa/w