REFILE-Typhoon bears down on Japan's main islands

(Corrects GMT time conversion in paragraph 4)

TOKYO, Oct 7 (Reuters) - A powerful typhoon approached Japan’s main islands on Wednesday, threatening the heavily populated country’s industrial centres with torrential rain and strong winds.

Typhoon Melor may be the most powerful storm to hit Japan’s main islands in more than 10 years if it makes landfall, the Meteorological Agency said.

Television showed waves pounding the shores of Japan’s small southern islands as the typhoon moved north-northeast towards the the main island of Honshu.

The eye of the storm was 250 km (155 miles) south of Tanegashima, 1000 km (620 miles) southwest of Tokyo and home to Japan’s rocket launch pad, at 10 a.m. JST (0100 GMT), according to the Meteorological Agency. It could make landfall in central Japan west of Tokyo on Thursday.

Up to 400 mm of rain is forecast over the next 24 hours in the Tokai region, which includes the industrial centre of Nagoya, the agency said, also warning of high winds, gales and flooding across southern Japan.

Toyota Motor Corp 7203.T may not open its plants in the Nagoya area on Thursday due to the typhoon.

“We haven’t decided whether to do daytime shifts tomorrow,” a Toyota spokeswoman said.

An official at Nippon Oil's 5001.T Oita refinery on the southern island of Kyushu said it was raining heavily but the typhoon had not affected the refinery's operations or oil shipments.

Nansei Sekiyu KK’s refinery in Okinawa said high seas were delaying some ships.

Melor, which had earlier been classed as a Category 5 Super Typhoon, is now a Category 1, according to storm tracking website Tropical Storm Risk. A Category 1 storm can bring winds of up to 153 km an hour.

Television news warned of similarities to a deadly 2004 typhoon at the same time of year that killed 95 people, brought transport to a halt and disrupted production.

An official at Tokyo’s city government offices said no additional measures were being taken to deal with the typhoon. An average of about three such storms hit Japan each year, although there were none last year. (Reporting by Isabel Reynolds, Nobuhiro Kubo and Osamu Tsukimori; Editing by Hugh Lawson)