FUKUI, Japan | Tue Apr 14, 2015 10:43am BST

A Japanese court on Tuesday issued an injunction to prevent the restart of two reactors citing safety concerns, in a blow to Prime Minister Shinzo Abe's push to return to atomic energy four years after the Fukushima crisis.

It is the second court ruling in less than a year against reactors operated by Kansai Electric Power, the country's most nuclear-reliant utility before Fukushima.

The ruling is a snub to Japan's beefed up nuclear safety after Fukushima and threatens to set back government plans to restart reactors deemed safe by the atomic regulator.

Kansai's reactors, located on the coast of Fukui prefecture in western Japan, have met basic safety regulations set by Japan's Nuclear Regulatory Agency (NRA) and were expected to be restarted some time this year.

"The fact that the court ruled in favor of the injunction after regulators had already given the go-ahead carries weight and will have an impact," said Hiroshi Segi, a former judge who is now critical of the judicial system because he feels it is often reluctant to challenge government policy.

Local residents had sought an injunction against the No. 3 and 4 reactors at Takahama, arguing that restart plans underestimated earthquake risks, failed to meet tougher safety standards and lacked credible evacuation measures.

Safety at the Takahama plant west of Tokyo cannot be assured and the regulator's standards "lack rationality," according to a copy of the ruling obtained by Reuters.

"This is a decision that has a decisive impact on nuclear restarts," Yuichi Kaido, a lawyer for the plaintiffs told a group of supporters outside the court, who cheered and waved banners including one saying, "The judiciary is still alive".