(Clarifies from campaigner that ruling is rare court victory not first)
TOKYO May 21 (Reuters) - A Japanese court ruled against allowing the restart of a nuclear power plant west of Tokyo on Wednesday, its operator said, a rare case in which anti-nuclear plaintiffs have successfully won a ruling to shut down reactors.
The court in Fukui prefecture ruled against allowing Kansai Electric Power Co to restart reactors No. 3 and 4 at its Ohi nuclear plant, the utility said in a statement, adding it would appeal against the decision.
Ohi, like all of Japan's nuclear plants, has been idled for safety checks in the wake of the 2011 disaster at Tokyo Electric Power Co's Fukushima Daiichi plant pending safety checks.
The court ruling is likely to be another spanner in the works for the return to operations of reactors, with the safety checks bogged down by paperwork and disputes over interpreting new guidelines.
"Plaintiffs have rarely won. This is right in the middle of the restart process ... it could have very well have repercussions," said Aileen Mioko Smith, executive director of Green Action, which earlier this month had a lawsuit to close the Ohi reactors rejected by a court in Osaka.
National broadcaster NHK said it was the first time anti-nuclear campaigners had won a court ruling against nuclear power, but Smith said there had been two other rulings by courts supporting plant closures.
Those rulings were eventually overturned by higher courts in favour of nuclear operators, she said.
Calls to Fukui District Court went unanswered. Anti-nuclear campaigners were seen on NHK celebrating the ruling. (Reporting by Aaron Sheldrick; Additional reporting by Osamu Tsukimori and Mari Saito; Editing by Nick Macfie)