TOKYO, Japan– A strong typhoon sweeping towards southern Japan on Tuesday triggered the cancellation of hundreds of flights as officials urged thousands of people to seek shelter. Typhoon Khanun was packing maximum sustained wind speeds of 162 kilometres (100 miles) an hour as it crossed the Pacific Ocean and was expected to start battering the Okinawa region late Tuesday. Cities across Okinawa issued non-mandatory evacuation orders to at least 370,000 people as the Japan Meteorological Agency warned waves of up to 12-metres (39-feet) high could pummel the group of islands. The agency said in its 0100 GMT update that the storm, which it described as "very strong" and "large", was about 240 kilometres southeast of the regional capital of Naha. Officials in Naha urged vulnerable residents to move to more secure locations in anticipation of strong winds and heavy rain. "Many people stay at home because their houses are concrete," a disaster management official at the Okinawa regional government told AFP, speaking on condition of anonymity. "But we are asking people who live alone or in wooden houses in low-lying areas to consider seeking shelter before the typhoon gets bad." More than 500 flights were cancelled on Tuesday, while regional ferry and bus services were suspended ahead of the typhoon, national broadcaster NHK reported. Japan Airlines and All Nippon Airways said more than 74,000 passengers in total would be affected by flight cancellations on Tuesday and Wednesday.