A second nuclear plant in Japan sits atop a possibly active seismic fault, government-appointed experts said Friday, days after the first facility was said to be at risk.

A panel appointed by the Nuclear Regulation Authority (NRA) said fractured strips of earth beneath the Higashidori plant's compound in northern Japan may be active faults, meaning it would likely have to be scrapped.

On Monday, geologists said it was probable that the Tsuruga nuclear plant in the centre of the country was sitting on faults that showed signs of geologically recent movement.

Active faults are those that, amongst other things, have moved within the past 120,000-130,000 years. Under government guidelines atomic installations cannot be sited on a fault if it is still classed as active.

NRA acting head Kunihiko Shimazaki said some of the fractures under the Higashidori plant compound may have resulted from tectonic movement in the past 100,000 years.

All but two of Japan's nuclear reactors remain offline after being shuttered for regular safety checks in the aftermath of the 2011 crisis at Fukushima, when a huge tsunami generated by an earthquake caused meltdowns.

They must now get the go-ahead from the newly-formed NRA before they can be restarted.

Japan's nuclear watchdog will make a formal assessment on the Higashidori plant next week.

The plant has one reactor which has been idled for checks, while construction of another reactor was suspended after last year's disaster, the worst atomic accident in a generation.

The NRA is also set to conduct inspections at four other plants including the Oi nuclear facility in western Japan, the country's only operating atomic power plant.

Hundreds of thousands of people were made homeless by the Fukushima accident, and tracts of prime agricultural land were left unfarmable after radiation spread across a large area.

Anti-nuclear sentiment is running high in Japan, which used to rely on atomic power for around a third of its electricity needs.