TOKYO (REUTERS) - The policy chief of Japanese Prime Minister Shinzo Abe's ruling party apologised on Wednesday and withdrew remarks that appeared to make light of the Fukushima nuclear disaster, adding it was up to the premier whether she would keep her job.

With a month to go before an election for parliament's upper house that Abe's Liberal Democratic Party (LDP) needs to win decisively to end a parliamentary deadlock and cement his grip on power, Abe and his aides are keen to ensure any PR fiascos.

In a speech on Monday, LDP policy chief Sanae Takaichi called for the restart of off-line nuclear reactors, noting that no one had died from the March 2011 Fukushima disaster.

In the world's worst nuclear disaster since Chernobyl, a massive earthquake and tsunami caused reactor meltdowns at Tokyo Electric Power Co's Fukushima plant, spewing radiation and forcing 160,000 people to flee their homes, many never to return.

There have been no known radiation deaths so far, but more than 1,000 people died from related causes such as suicide and delayed medical care as a result of evacuations.

Takaichi's remarks came under fire from opposition parties, members of her own party and media and prompted a warning from Chief Cabinet Secretary Yoshihide Suga that politicians should watch what they say.

Takaichi apologised and told reporters that she was withdrawing the remarks. "I am withdrawing all my comments regarding energy policy," she told reporters. "It is inexcusable if my remarks caused bitter feelings and anger." Asked about opposition demands that she resign, Takaichi told reporters that her fate was up to Abe, media said.

The LDP has a hefty lead over opposition parties and Abe's support rates remain high, but they have slipped a bit in recent opinion polls as a slide in Tokyo share prices reflects growing concern over whether his "Abenomics" policy prescription to end stagnation will succeed.

A June 7-10 survey by Jiji news agency showed a 2.8 point drop to 57.4 per cent, the second decline since he took office in December following the LDP's big election win.

Abe's first term as premier ended abruptly in September 2007 when he quit after a year marked by scandals in his cabinet, public outrage over lost pension records, a stunning defeat in an upper house election and ill health.

Abe and his aides are intent on not repeating past mistakes.