Japan has switched on the first nuclear reactor after a two-year ban brought on by the 2011 Fukushima meltdown.

The Japanese government and Sendai power plant operators say the nuclear reactor will operate under stringent conditions.

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There’s still widespread concern and distrust on the use of nuclear energy and Japanese media reported around 200 people protested outside the plant in Satsumasendai region on Tuesday.

“The reactor No.1 at the Sendai nuclear power plant started operating at 10.30am (11.30am AEST),” said a spokesman for Kyushu Electric Power, which operates the reactor about 1000 kilometres southwest of Tokyo.

The restart comes more than four years after a quake-generated tsunami triggered meltdowns at the Fukushima plant, prompting the shutdown of Japan’s stable of reactors.

The government, which has faced huge pressure over energy, says the 31-year-old reactor will operate under new, stricter conditions introduced following the Fukushima meltdown.

The atomic accident – one of the worst in modern history – displaced 160,000 people from the surrounding region who are still unable to return because of high radiation levels.

Japan has relied on nuclear energy to deliver a quarter of its energy needs but has relied on costlier oil and natural gas imports since the nuclear plant shut down.

The Sendai plant is located near active volcanos and one of Japan’s most active is only 50 kilometres away.

Operators of the plant say they can remove the nuclear fuel in the event of an eruption.

Commercial operations at the Sendai plant are due to begin next month.

– with AAP