MANILA, July 14 (REUTERS) - Typhoon Basyang cut power supplies across Metro Manila and surrounding provinces as it moved across the main Philippine island of Luzon to the South China Sea, but the stock exchange said it would operate as normal on Wednesday.

Basyang, a category 1 typhoon with winds of 90 kph and gusts of up to 120 kph, was moving west-northwest at 22 kph and will be over South China Sea late on Wednesday.

Wide areas of the capital and nearby provinces were plunged into darkness late on Tuesday as the national grid declared a systems outage, and power was still not restored on Wednesday morning.

Buildings in the business district were being powered by back-up generators after the first sizeable typhoon of the season hit the country.

Dozens of domestic and international flights were either suspended or diverted from Manila's main airport. Schools were closed but government offices are open as the country began cleaning up the debris left by Basyang, known internationally as Conson.