A Japanese company Tuesday unveiled a cheap Geiger counter for the iPhone to enable people worried about the March Fukushima nuclear accident to check their environment for radiation.

The probe, 14 centimetres long by five wide (six inches by two), connects to the iPhone and the screen displays radiation readings in combination with a special app such as the Geiger Bot.

The device was developed on the initiative of a young researcher who wanted to make a cheap and easy-to-use Geiger counter available following the world's worst nuclear disaster since Chernobyl.

"Immediately after the disaster triggered by the earthquake and tsunami of March 11 in the northeast of the archipelago, the cheapest Geiger counters cost 60,000 yen ($780, 570 euros) and were hard to find," said Takuma Mori on the origins of the device made by Sanwa Corp.

The first models for iPhones will go on sale in the next few days priced at 9,800 yen ($127).

Japan has been on alert for the impact of radiation since the devastating tsunami crippled the Fukushima Daiichi nuclear power plant.

Its cooling systems were knocked offline and reactors were sent into meltdown, resulting in the leaking of radiation into the air, oceans and food chain and causing concern among the population.

Radiation hotspots have been discovered in various regions, some of which were unrelated to the nuclear disaster.