Japan's new nuclear regulator said Wednesday it was going to require power companies to make reactors terror proof as well as quake resistant, as the body set out to prove it was a watchdog with teeth.

Shunichi Tanaka, chairman of the Nuclear Regulation Authority, said plants would have to be able to survive a direct hit from a hijacked airliner or ship, as well as withstand tsunamis like the one that crippled Fukushima.

"For absolutely sure, if we continue... Japan will have the world's toughest standards in terms of earthquakes and tsunami," Tanaka told a press conference.

The move comes after repeated criticism that lax regulation and an overly-cozy relationship between authorities and the big-money companies they were supposed to police worsened the catastrophe of March 2011, when a tsunami swamped the coastal Fukushima Daiichi plant.

Thousands of people were forced to evacuate when radiation spewed from the crippled plant, polluting swathes of land and leaving some settlements uninhabitable, possibly forever.

The NRA this week unveiled draft proposals for new safety measures designed to prevent a repeat of the world's worst nuclear accident in a generation.

Under the plans, which will be formally adopted in July, power plants must build backup control rooms and secure emergency power supplies on higher ground 100 metres (110 yards) from reactors.

Cooling systems at Fukushima and emergency power supplies were located in the same building as the reactors that went into meltdown.

The Authority wants nuclear plants to prepare for "external human-caused events" including: "flying objects such as falling planes, the collapse of a dam, explosions, fire at nearby plants, toxic gas, a ship crashing into a facility and the interruption of communication systems".

The nuclear authority is also crafting new safety criteria to deal with earthquakes and tsunami, including toughening the regulations on siting a plant near geological fault lines.

Once adopted, Japanese regulations will match standards in the United States, which tightened its nuclear rules after the terror attacks on September 11, 2001.

The move is partially designed to symbolise a change in the nation's nuclear outlook, which has been lambasted in the aftermath of the meltdowns.

Fukushima operator Tokyo Electric Power has insisted it could not reasonably have predicted the massive tsunami that slammed into Japan after the 9.0 magnitude undersea earthquake.

But in October the company admitted it had played down the risks to the facility for fear of the political, financial and reputational cost.

Anti-nuclear protests grew in Japan over 2012, with increasing outrage over the political and financial clout of one of the world's largest utilities, which has enjoyed a monopoly for decades on the production and distribution of electricity in and around Tokyo.

Japan's stable of 50 reactors was gradually shut down in the months after the catastrophe as scheduled safety checks fell due.

A nervous public has prevented any more than two of them being restarted since, despite warnings of a power crunch.

Tanaka said Wednesday the two working reactors must also be taken offline if they fail to meet the new standards.