China will air-drop shrimps and maize over the nation's largest freshwater lake where hundreds of thousands of birds are at risk of hunger due to drought, an official said Wednesday.

Poyang Lake in east China's Jiangxi province -- a major winter destination for birds in Asia such as the Hooded Crane -- is drying up due to low rainfall, affecting the availability of plankton, fish and waterweed that birds feed on.

"Since November last year, nearly 200,000 migratory birds have come for the winter," Zhao Jinsheng, head of the animal and plant protection department at the Poyang Nature Reserve, told AFP.

"Food is starting to be scarce and there is still some time before they leave in March, so we decided to use a helicopter to air-drop food, to help the birds last through winter."

He said officials had not yet decided when the first air delivery would be, but the official Xinhua news agency said it would take place before the Chinese Lunar New Year, which begins on January 23.

The helicopter will air-drop millet, maize and shrimps on wetlands and on the surface of water areas, Zhao added.

Wu Heping, a senior official at the reserve, was quoted by Xinhua as saying that in previous times of need -- such as severe snowstorms -- staff at the reserve have distributed food by hand.

But this year's drought has forced birds into a wider area around the lake, with thousands flying to the nine satellite lakes of Poyang, which is why authorities decided to use air distribution.

China is regularly affected by crippling dry spells. Last spring, authorities said a drought along the Yangtze river had affected more than 34 million people, leaving livestock without water and parching a major grain belt.

Last week, Poyang Lake spanned an area of just 183 square kilometres (71 square miles), compared to the 4,500-square-kilometres it can reach when at full capacity -- more than six times the size of Singapore.