China issued an alert Sunday for approaching tropical storm Kestana, which left at least 51 people dead and 21 others missing in the Philippines Saturday.

Kestana, the 16th tropical storm this year, was located at 910 kilometers southeast of Sanya City in southern China's Hainan Province at 5 a.m. Sunday. It contains winds of up to 90 km per hour at its center and is moving northwestward at 20 km an hour, the central observatory said.

The observatory forecasts the tropical storm will continue strengthening and would hit southern coastal areas of Hainan or pass through the southern coast of Hainan to lash coastal regions in Vietnam on Tuesday or Wednesday. It ordered boats in Kestana's path to return to harbor.

The tropical storm made landfall on the northeastern Philippines coast Saturday noon and triggered heavy rainfall in metropolitan Manila for six hours ending 2 p.m. Saturday.