Nuclear power plants close to the epicentre of a powerful undersea earthquake and tsunami off Japan have reported no problems and no emergency measures were activated, the UN atomic agency said Friday.

"Nuclear power plants in the region nearest to the epicentre of the earthquake have reported to (Japan's nuclear authority) the NRA that they have detected no trouble," the International Atomic Energy Agency said.

The Nuclear Regulation Authority report, made through the Unified System for Information Exchange in Incidents and Emergencies (USIE), has been distributed to all official contact points in member states and international organisations, the IAEA said.

The 7.3 quake struck 36 kilometres (23 miles) under the Pacific, the US Geological Survey said, causing a 1.0-meter (3.3-feet) rise in sea levels at some points. A tsunami warning was later lifted and there were no immediate reports of any fatalities.

In March 2011, a devastating earthquake and tsunami killed thousands of people and sent multiple reactors at the decades-old Fukushima nuclear plant into meltdown, spewing radiation over a wide area in the world's worst atomic disaster in 25 years.