BEIJING - Typhoon Muifa gained strength in the East China Sea on Wednesday forcing the cancellation of hundreds of flights out of the financial hub of Shanghai and threatening the busy port shared by Ningbo and Zhoushan cities.

Zhejiang province upgraded its typhoon emergency response to the highest level as Muifa is expected to move north-west at a speed of 20-25 kmh, intensifying and eventually reaching coastal areas south of Zhoushan, according to the China Meteorological Administration.

China's 12th cyclone of the year was expected to make landfall on Wednesday afternoon or night, according to forecasters.

Shanghai issued an advisory warning for wind gusts and heavy rains are expected until Thursday.

More than 50 per cent of flights will be reduced or cancelled at Shanghai Pudong Airport and Hongqiao Airport on Wednesday with 589 flights already affected, according to state media.

Flights at Zhoushan and Ningbo airports were also cancelled.

Zhejiang authorities issued a "red warning" for flash floods in several areas and the national weather forecaster said there was a high risk of flooding of small and medium-sized rivers in north-east Zhejiang and waterlogging in eastern and northern Zhejiang, Shanghai, southern areas of Jiangsu and other places.

China’s bunkering hub Ningbo-Zhoushan has also temporarily suspended discharging and loading oil, while tankers are ordered to stay at anchorages.

“Oil tankers will not be allowed to call at ports until the typhoon leaves. And port services will also suspended over the period,” an official from Zhejiang Maritime Safety Administration said on Wednesday.

Ningbo-Zhoushan is one of China’s busiest oil ports, consisting of 11 300,000 tonne-class crude oil berths for Very Large Crude Carriers(VLCC) to call.

It is not clear when the port services will be resumed. REUTERS