Japan's push to restart nuclear reactors shut for maintenance by proving their safety through stress tests and plans to let them operate for as long as 60 years have sparked an angry response from the public, wary of atomic power in the aftermath of the Fukushima disaster.

In a rare protest, a group of citizen observers delayed for hours a hearing at the trade ministry on Wednesday, at which the nuclear watchdog presented to experts its first completed review of stress test results for two reactors from Fukui prefecture's Ohi nuclear power plant.

The watchdog, Nuclear and Industrial Safety Agency (NISA), said in a draft report the tests showed the reactors were capable of withstanding a severe shock similar to the magnitude 9.0 earthquake and tsunami that crippled the Fukushima plant. But the report's review by a panel of experts is set to continue after observers demanded access to the deliberations and questioned the expert panel's impartiality.

Once the stress test results are approved, Japan will still need the green light from local governments hosting nuclear power plants for the reactors to be restarted.

Local officials, however, say the stress tests are not enough, with some requesting that findings from the Fukushima disaster also be considered.

As the governor (of Fukui) has been saying, there is no change to our stance that a provisional safety standard based on findings from Fukushima is essential for a restart of the reactors, said an official at Fukui prefecture's safety and environment department.

We will keep demanding the government to come up with such a standard, he said. The official, who declined to be named because he was not authorised to speak to the press.

Shinobu Tokioka, the mayor of Fukui's Ohi town said: If local fears were to be dispelled over reactor restarts it was important for the government to come up with a comprehensive set of safety standards and measures based on information from the Fukushima accident.

The government and the parliament are leading separate probes into the disaster but their findings are not due until the summer. By then all of Japan's 54 reactors will be shut down if those taken offline for checks fail to win approval for restarts.

Some residents want local reactors to be shut down for good despite the financial benefits they have brought to local communities.

The stress tests won't solve anything. The people of Fukui cannot accept them, said Takatoshi Yamazaki, a leader of a civic group calling for a permanent shutdown of nuclear reactors in the prefecture. Yamazaki said the reactors were simply too old to operate safely.

EXTENSIONS

The government's decision this week to allow nuclear reactors to operate for up to an additional 20 years, in addition to an initially proposed 40-year limit also drew fire from local communities hosting nuclear power plants.

Public broadcaster NHK quoted Tatsuya Murakami, mayor of Tokai village in Ibaraki prefecture, as saying that allowing for an additional 20 years of service is a compromise that guts the substance of the original plan.

Yukiko Kada, governor of Shiga prefecture, also said that allowing the reactors to operate for up to 60 years will make the public uneasy about nuclear safety measures.

The central government ordered stress tests to overcome public opposition to the restarting of reactors shut down for regular checks after meltdowns at the Fukushima plant shattered public confidence in atomic safety.

The world's worst nuclear disaster in 25 years has prompted a major shift in Japan's energy policy, with the country now looking to reduce its reliance on nuclear power. It had aimed to increase its share prior to the disaster.

But the government is also keen to avert a crippling power crunch in the short term if nuclear reactors are not restarted. Only five remain in operation with the rest shut for routine checks.

The basic policy is to reduce reliance on nuclear power in the medium to long term. But when considering the economy, the question is how to cope by suddenly switching off nuclear power when there are no substitute energy sources, and if this is feasible, Chief Cabinet Secretary Osamu Fujimura told reporters on Thursday.

(Editing by Tomasz Janowski and Chris Gallagher)