An earthquake with a magnitude of 7.4 has triggered tsunami warnings across Japan.

The quake, which was felt in Tokyo, was centred 67 km northeast of Iwaki off the coast of Fukushima.

A tsunami of up to one metre (three feet) was observed in the area, following the quake shortly before 6am local time, Japanese media reported.

According to public broadcaster NHK, the Tokyo Electric Power Co said there was no damage to any of its power plants.

There were no immediate reports of damage or injury.

Fukushima is home to the nuclear power plant that was destroyed by a huge tsunami following an offshore earthquake in 2011, spilling radiation out into the air and sea.

The earthquake that caused that disaster was magnitude 9, the strongest quake in Japan on record.