Technicians are battling to stabilise a third reactor at a quake-stricken Japanese nuclear plant that has been rocked by a second blast in three days.

Sea water is being pumped into reactor 2 at the Fukushima Daiichi plant after its fuel rods were fully exposed twice.

International nuclear watchdogs said there was no sign of a meltdown but one minister said a melting of rods was "highly likely" to be happening.

The crisis was sparked by Friday's 9.0-magnitude quake and tsunami.

Thousands of people are believed to have died, and millions are spending a fourth night without water, food, electricity or gas. More than 500,000 people have been left homeless. [ BBC NEWS ]