Beijing: China may struggle to repeat bumper harvests of recent years as adverse weather affects crops and planting, an official from the National Development and Reform Commission said.

"It will be hard to have a bumper harvest this year after the consistent grain production growth in the past six years," said Fang Yan, deputy director of the Rural Economy Department at the top state planning agency. "The adverse weather is a prominent factor."

China's leaders have prioritised food security to ensure that the world's most-populous nation has adequate supplies, maintaining stockpiles of about 40 per cent of annual consumption. Premier Wen Jiabao said meeting a goal of growing 500 million tonnes of grains would be a test, according to a March 25 report.

"We experienced the worst drought in over 50 years in the southwest, persistent low temperatures in the north which delayed spring planting by 7-10 days, snow and ice in the northeast and flooding in northern Xinjiang caused by melting snow," said Fang, who spoke at a conference in Sanya, Hainan.

China's 500 million tonne grain-output target is lower than last year's harvest of 530.8 million tonnes, Xinhua said in a March report. Food self-sufficiency remains a priority for China because relying on other producers isn't sustainable, Vice-Minister for Agriculture Niu Dun told a conference in January.

The drought in China's southwest, which may have been caused by the El Nino weather phenomenon, extends southward into Southeast Asia. The Mekong River, which flows from China through five countries including Cambodia and Vietnam, is at its lowest level in 30 years, Thailand's Department of Water Resources said March 10.