The operator of the Fukushima nuclear plant has managed to restore the cooling system in a pool which holds hundreds of tonnes of spent nuclear fuel at the facility.

The system had failed earlier, causing the pool's temperature to rise.

TEPCO says a fault caused the cooling system to shutdown and then a back up system failed to activate.

The pool contains more than 1,500 nuclear assemblies, the vast majority of them containing highly radioactive fuel rods.

There were fears that if the problem was not fixed, the pool could reach its maximum safe temperature of 65 degrees Celsius by Tuesday.

The temperature in the damaged pool touched 43 degrees before the fault was fixed.

TEPCO says it should now gradually fall back to normal.

Meanwhile, Japan is due to restart its first nuclear reactor since the crisis hit Fukushima last year.

Hundreds have gathered near the plant in the town of Oi to protest the move, which has divided public opinion.

Last month, prime minister Yoshihiko Noda urged support for the plant, saying a return to nuclear power was essential for the economy.

All 50 of Japan's plants were shut after the meltdown at Fukushima, which was triggered by a tsunami and earthquake.

ABC/BBC