An earthquake of magnitude 7.3 struck today off Japan’s east coast, the US Geological Survey said, and Japan’s emergency agencies issued a tsunami advisory for the region that includes the crippled Fukushima nuclear site.

The UN's Atomic Agency is visiting Japan's Fukushima nuclear power station to assess the scale of the leaks which have plagued the site in recent months.

The operator of Japan’s crippled Fukushima Dai-ichi nuclear plant is preparing to open a door of a reactor building to allow workers to install a cooling system and equipment to prevent an explosion.