China's chief statistician has acted to improve the country's crop data, which are widely viewed as exaggerating harvests, and exhorted regional officials to provide accurate figures.

Ma Jiantang, the head of China's National Bureau of Statistics, stressed the importance of reliable and timely data for the government to make "scientific" decisions relating to grain consumption, production and trade.

His request, made on a tour of the eastern wheat growing region of Henan, for local statistics bureaux to promote accuracy, follows concern both in China and abroad that a subsidy regime which pays regional authorities by production may be leading to distortions.

US Department of Agriculture officials in Beijing in March restated warnings that "to gain more allocation of financial aid from the central government, provincial government authorities are occasionally tempted to overstate their grain output".

Conflicting statistics

Data concerns have centred on corn - which has jumped to record highs in many areas, prompting processors to seek cheaper US imports, and giving credibility to assessments that last year's crop may have fallen significantly short of the 164m tonnes publised in official forecasts.

The USDA has estimated the crop at 155m tonnes, with China-based analysis group Shangha JC Intelligence putting it at some 140m tonnes.

However, USDA officials earlier this month also flagged discrepancies in soybeans, which appeared to show farmers in Heilongjiang, the biggest producing province, selling 34% more 2009 crop than they had harvested.

Inflation impact

Ma Jiantang, 52, comes from a trade rather than agricultural background, with previous positions including a spell as deputy secretary-general of China's State Economic and Trade Commission.

At the NBS, he is responsible for series of key statistical announcements, including a prediction in January that Chinese inflation would be contained this year, a forecast in which he highlighted an assessment of grain supplies compared with demand.