Kansai Electric Power Co. fell by the most in more than 28 years, leading Japanese utilities lower after a court injunction prevented the company from operating two nuclear reactors, threatening the country’s return to atomic power five years after the Fukushima disaster.

Kansai Electric, Japan’s second-largest power utility, closed down 15 percent at 1,047 yen in Tokyo on Thursday, the biggest drop since October 1987. The 20-member Topix Electronic Power & Gas Index slumped 3.1 percent, compared with a 1.5 percent rise in the broader index.

The Otsu District Court cited safety concerns in issuing the injunction Wednesday in a decision that applies to the plant’s No. 3 and No. 4 reactors at its Takahama plant, according to court documents. The utility said it will begin shutting its No. 3 unit on Thursday.

The ruling is a setback for Prime Minister Shinzo Abe, who has backed the return of atomic power after the 2011 Fukushima disaster led to the shutdown of the country’s entire nuclear fleet. Kansai resumed operations at its Takahama No. 3 unit in January and the No. 4 unit in February before the latter was placed in cold shutdown on March 2 after an alarm.

“This is a reminder that there is still a long way to go to restore public trust in the nuclear industry following Fukushima,” James Taverner, a Tokyo-based analyst at consultant IHS Inc. said in an e-mail. “The success of this injunction (even if temporary) will likely encourage other groups of local residents to seek similar injunctions for other nuclear plants.”

Kyushu Electric Power Co., which restarted two of its nuclear reactors last year, fell 8 percent to 1,063 yen, the biggest decline since June 2013.