China's maritime forecasting authority warned Tuesday of approaching Typhoon Saola, the ninth typhoon of the year, and called on vessels and local residents to be well-prepared.

Typhoon Saola is gaining strength and will move northwest at a speed of 10 km per hour toward the east coast of Taiwan and gradually approach the Chinese mainland's coastal areas, the National Marine Environmental Forecasting Center said in a report.

The typhoon's center was about 400 km southeast of Hualien, Taiwan, Tuesday morning, the report said.

The center issued a yellow warning for waves on Tuesday, the second-lowest level in China's four-level storm and wave warning system.

From noon Tuesday to noon Wednesday, waters east of Taiwan will produce waves 7 to 10 meters high, while the southern waters of the East China Sea, the Taiwan Strait and the northeastern waters of the South China Sea will see waves 4 to 6 meters high.

The country's Fujian and Zhejiang provinces will also witness 2.5- to 3.5-meter high waves during the same period, according to the center's forecast.

The center also issued a blue warning, the lowest warning level, of a storm surge at the coastal area of Fujian, with a forecasted surge of 30 to 80 centimeters from Tuesday afternoon to Wednesday morning.

The center warned local authorities and the public to take precautionary measures and intensify safety checks on fishing facilities.