Typhoon Kajiki has brought strong winds and heavy rain to southern China's Hainan island and parts of Guangdong province.

Vietnam announced plans to evacuate more than half a million people and ordered boats to stay ashore, while the southern Chinese city of Sanya closed businesses and public transport on Sunday as both braced for an intensifying Typhoon Kajiki.

Typhoon Kajiki is battering the coast with heavy rains and strong winds, as authorities warn it could cause flash floods and landslides.