A group of Japanese citizens filed a lawsuit Monday to prevent the restart of a nuclear power plant, a day after the first anniversary of the tsunami that sparked the Fukushima atomic disaster.

The group of 259 citizens filed the suit in Osaka District Court seeking an injunction that would block the reopening of utility Kansai Electric's nuclear power plants Oi Unit 3 and 4 in central Fukui prefecture.

On Sunday, tens of thousands rallied near Japan's crippled Fukushima plant demanding an end to nuclear power after the earthquake and tsunami on March 11 last year sparked meltdowns at the stricken plant.

The tsunami swamped cooling systems at the Fukushima site and sent three reactors into meltdown, spewing radiation into the environment.

Kiyoko Shimada, a member of the group organising the lawsuit, told AFP that plans to reopen the Oi reactors were premature.

"These reactors are said to be the first in line for the restart of nuclear power plants in Japan after the accident in Fukushima, but given that there are lots of unanswered questions over the Fukushima Daiichi plant, it is too early to restart," she said.

"The Oi plants are near active faults and some experts say the plants' quake resistance is not sufficient."

The Japanese government is reportedly planning to approve the restart of the Oi plants as early as this month.

In a statement, Kansai Electric said: "Although we decline to comment on the lawsuit as we don't know the details of the claim, we will make efforts in explaining to the public that we've taken every measure to operate nuclear reactors safely."

Since last year's accident, the country's commercial nuclear power plants have been undergoing safety inspections with just two out of 54 reactors currently online.

Prime Minister Yoshihiko Noda pledged Sunday to "make every effort" to get local approval before restarting nuclear reactors, a move deemed necessary to to avoid potential power shortages across Japan, Kyodo News reported.

The world's worst nuclear accident in quarter of a century has heightened fears in Japan over atomic power, with several citizen groups having filed or preparing to file injunctions to block other plant restarts.