A Japanese man has been arrested for landing a drone on the prime minister's residence with a minuscule amount of radiation in an apparent protest against the use of nuclear power, four years after the Fukushima disaster.

Unemployed man Yasuo Yamamoto, 40, who lives in Fukui Prefecture in western Japan, was arrested on Friday and charged with obstruction of official business, police said.

The maximum penalty is three years in prison or a 500,000 yen ($5,370) fine.

Japanese media reported that Yamamoto turned himself in at a police station in Fukui and said he landed the drone as a protest against nuclear power.

Yamamoto faces a charge of "forcible obstruction of business" by having officials deal with the drone, a spokesman at the Tokyo Metropolitan Police said.

"The suspect planned to disrupt operations at the prime minister's official residence," the spokesman said.

Staff at the official residence, known as the Kantei, discovered the 50-centimetre drone on top of the five-storey structure in central Tokyo on Wednesday morning.

The radiation was so low it was not harmful to humans.

Blog posts claimed drone was carrying radioactive sand

Yamamoto blogged that the drone carried radioactive sand in a bottle from Fukushima and a card voicing his opposition to atomic energy, reports said.

The blog also said Yamamoto sent the drone on April 9, almost two weeks before it was found, and planned to land it in front of the premier's office but that he lost control of the machine and did not know where it had gone.

A later post complained that it took two weeks for officials to find the drone, while also voicing a nervous feeling.

"This is how a criminal must feel when seeing media reports about your own crime," he wrote.

No-one had been on the roof since Mr Abe used the helipad on March 22.

There are currently no legal restrictions on the use of drones, which are becoming popular in Japan particularly for aerial surveying, photography and video shoots.

Following the incident, the government said it would consider regulating drone flights.

Reports said the Japanese government also instructed the monitoring of airspace above important facilities be beefed up, including over nuclear power plants and airports.

A Japanese court on Wednesday approved the restart of a nuclear power station in the south-west of the country, rejecting concerns about nuclear safety in the wake of the 2011 Fukushima radiation disaster.

An earthquake and tsunami triggered meltdowns at a nuclear power plant in Fukushima in the worst nuclear crisis since Chernobyl, 25 years earlier.

AFP/Reuters