HAIKOU -- A tropical depression escalated to a typhoon on Tuesday morning over the sea to the east of the Philippines and is approaching the South China Sea, according to the meteorological service in south China's Hainan province.

Saudel, the 17th typhoon to affect China this year, is expected to hit the South China Sea on Wednesday and bring torrential downpours and strong winds to the island province of Hainan from Friday to Sunday.

The provincial meteorological department has asked seagoing boats to return to ports immediately and warned of potential disasters including possible flooding in medium and small rivers, urban flooding, and geological disasters in mountainous areas.