By Elaine Lies
TOKYO, July 8 (Reuters) - Hundreds of flights were cancelled in Japan and more than 500,000 people urged to evacuate as a powerful typhoon brought torrential rain and high winds to southwestern islands and was forecast to reach Tokyo later in the week.
Typhoon Neoguri weakened from its original status as a super typhoon but remained intense, with gusts of more than 250 km per hour (155 mph). It was powering towards the Okinawa island chain where emergency rain and high-seas warnings were in effect.
The storm will be at its most powerful as it passes Okinawa, some 1,600 km (1,000 miles) southwest of Tokyo on Tuesday, but the Japan Meteorological Agency (JMA) warned of heavy rains and potential flooding in Kyushu, the westernmost of Japan's main islands, as well as heavy rain in the rest of the nation as the storm turns east.
"People must take the utmost caution," Keiji Furuya, state minister in charge of disaster management, told a news conference.
One man was missing after his boat was swamped by high waves, NHK national television said. Several people suffered minor injuries from falls.
More than 50,000 households in Okinawa lost power and an oil refinery halted operations. Television footage showed street lights rocking in high winds and branches being blown down largely deserted streets.
There are no nuclear plants on Okinawa but there are two on Kyushu, which lies in the area through which the typhoon is likely to pass after hitting Okinawa. There is another on Shikoku island, which borders Kyushu and could also be affected.
All are shut down due to national policy and the Fukushima Daiichi nuclear plant, which was wrecked by an earthquake and tsunami in March 2011, is on the other side of the country.
"When the wind blows most strongly, it's impossible to stand. You have to hold on to something," said Kei Shima, a self-employed Okinawa resident in her 30s.
"The lights are fading in and out, like the house is haunted. The rain is getting stronger and falling sideways."
Neoguri was roughly 110 km (68 miles) southwest of Kumejima of island at noon (0300 GMT) and moving north at 25 kph (16 mph), with sustained winds of 180 kph (110 mph).
Kadena Air Base, one of the largest U.S. military facilities on Okinawa, was on its highest level of storm alert and all outside activity was prohibited.
Nansei Sekiyu KK, a Japanese refiner wholly owned by Brazil's Petrobras, said it had suspended oil refining operations at its 100,000 barrels-per-day Nishihara refinery in Okinawa on Monday evening.
A JMA official said the storm will maintain its strength as it heads north but gradually turn to the east, making landfall in Kyushu before raking its way up the main island of Honshu and coming close to Tokyo on Friday.
"But it will be weaker by then, so that Tokyo can mainly expect a lot of rain, and maybe some gusts of wind," he added.
Around two to four typhoons make landfall in Japan each year but they are unusual in July. (Additional reporting by Oliver Fabre,; Editing by Nick Macfie)