A strong earthquake has rocked north-eastern Japan, which is still recovering from the devastating tsunami six months ago. The quake had a preliminary magnitude of 5.6. There were no immediate reports of damage and no tsunami warning was issued. The earthquake was centred off Fukushima, which was severely hit by the quake and tsunami in March that left more than 21,000 people dead or missing. The March disaster touched off the worst nuclear crisis since Chernobyl, generating meltdowns, fires and explosions at the Fukushima Dai-ichi nuclear facility. The plant\'s operator said there were no signs of abnormalities at the plant from the latest quake.