TOKYO, Aug 2 (Reuters) - High winds hit power lines in Japan's Okinawa and knocked out electricity to more than 200,000 households on Wednesday morning, as powerful and slow-moving typhoon Khanun neared the country's southwestern islands threatening torrential rains.

Hundreds of thousands of people in the tropical prefecture, a popular tourist destination some 1,600 km (1,000 miles) southwest of Japan's capital Tokyo, were advised to evacuate as the storm moved northwest at speed of 10 kph (6.2 mph), according to the Japan Meteorological Agency.

Local utility Okinawa Electric Power (9511.T) said 218,260 households, or 34% of all houses covered, were experiencing power outages as of 9:00 a.m. Japan time (0000 GMT), according to its website.

In Okinawa's capital city Naha, the airport was entirely closed for a second day on Wednesday. More than 400 flights were already cancelled as of morning with at least 65,000 passengers affected, according to public broadcaster NHK.

The storm is hitting during the peak summer tourist season, which this year has seen the number of visitors return to pre-pandemic levels. Okinawa is frequently hit by typhoons, but usually later in the year.