China has said that it could face "uncertain factors" in its wheat and corn harvests for the rest of the year, as prospects for many global agricultural products exporters, such as the United States, are also bleak due to excessive heat.

Despite an increase in crop output in the first half, a senior official on Wednesday warned about uncertainties in corn and wheat yields, noting that a sustained raise of agricultural production could be difficult.

Zhang Ping, director of the National Development and Reform Commission, made the remarks while delivering an economic report to the top legislature, the National People's Congress Standing Committee.

According to a US government survey earlier this month, the prospects for corn and soybean crops in the US - the world's largest food exporter - could weaken further due to prevailing midsummer heat.

Heat waves have also scorched hopes in other major agricultural products exporters, such as Russia, India and Ukraine, prompting economists to estimate that worldwide crop prices will keep surging.

Zhang said there is a possibility that crop yields in the fall will be hit by natural disasters, plant diseases and pests, while pledging for more favorable policies and technical assistance to help farmers deal with those issues.