TOKYO, Sep 19 (Reuters) - Typhoon Nanmadol pounded western Japan with heavy rain and strong winds on Monday (Sep 19), forcing airlines to cancel flights, snarling train operations and leaving more than 300,000 households without power.

Authorities warned of floods and landslides as the 14th typhoon of the season moved toward eastern Japan.

Up to 400mm of rain is expected in central Japan's Tokai region, the nation's industrial heartland, over the next 24 hours, the Japanese Meteorological Agency said.

"We need to remain highly vigilant for heavy rains, gales, high waves and storm surges," an agency official said at a news conference.

Television footage showed a toppled traffic signal and submerged farmlands.

Kyushu Railway, the train operator serving Japan's western major island of Kyushu, said it had halted operations for all of Monday, while Japan Airlines and ANA Holdings have cancelled about 800 flights for the day, public broadcaster NHK reported.

About 340,000 households, most of them in Kyushu, were without electricity as of early Monday morning, the trade ministry said.