Japan earthquake: Explosion at Japanese nuclear plant

A massive explosion has struck a Japanese nuclear power plant after Friday's earthquake.

Pictures show a blast at the Fukushima plant and reports say several workers were injured.

Japanese officials fear a meltdown at one of the plant's reactors after radioactive material was detected outside it.

A huge relief operation is under way after the 8.9-magnitude earthquake and tsunami, which killed more than 600.

Humphrey Hawksley reports.