A typhoon, described as the "strongest in 10 years," was closing in on Japan Tuesday, on a path that will take it towards the precarious Fukushima nuclear power plant.
Typhoon Wipha, packing winds of nearly 200 kilometres (125 miles) per hour near its centre and bringing heavy rains, was in the Pacific south of Japan Tuesday evening and moving north at 35 kilometres per hour, the Japan Meteorological Agency said.
It was forecast to reach an area off the Tokyo metropolitan area by early Wednesday and later in the day would be off the coast of Fukushima where the crippled nuclear power plant sits.
"It is the strongest typhoon in 10 years to pass the Kanto region (Tokyo and its vicinity)," Hiroyuki Uchida, the agency's chief forecaster, told a news conference.
"It is expected to have a great impact on the traffic systems in the metropolitan area during commuting hours," he said.
As the weather agency issued warnings of torrential rain and strong winds, the operator of the Fukushima plant, Tokyo Electric Power Co. (TEPCO), said it was bracing for the storm after a series of leaks of radiation-polluted water.
"We are making preparations for proper management of contaminated water... We will patrol places that could have inflows of water (from the storm)," a company spokesman said.
Cables and hoses have been bundled together, while ground and off-shore works have been halted, he said.
Earlier this month the company announced 430 litres (114 US gallons) of polluted water had spilt from a tank as workers tried to remove rainwater dumped at the plant by recent typhoons.
It has admitted contaminated water may well have flowed into the sea.
Japan's atomic watchdog summoned the president of TEPCO for a public dressing-down for sloppy standards at the plant after the incident.
The nuclear plant was badly damaged by the tsunami that hit in March 2011. Critics say it remains in a fragile state and at the mercy of extreme weather or other natural hazards.