China's top statistician has accused local officials of "falsifying" economic figures and warned offenders would be severely punished, reflecting growing concern about the reliability of government data.

"Currently, there have been occasional cases of local sectors falsifying statistics and practising fraud, which violate statistical laws and regulations," Ning Jizhe, director of the National Bureau of Statistics, wrote in the Communist Party mouthpiece People's Daily on Thursday.

He said Beijing had "zero tolerance" of fakers and violators would "pay a genuinely high cost" as authorities tried to "create an environment where they will not dare, not imagine, not think of breaking the law".

"A number of cases that involved the falsification of statistics were investigated and dealt with," he said, adding that "administrative punishments have been carried out".

Officials and analysts in China and abroad have long questioned the accuracy of Chinese economic figures, which many suspect are often manipulated to make the economy look more robust than it really is.

One of the problems has been that local bureaucrats' promotions are tied to economic performance, giving them an incentive to falsify data in hopes of improving their chances of career advancement.

Even Premier Li Keqiang has expressed doubts about the reliability of the country's statistics.

Leaked US diplomatic cables show that as the top official in Liaoning province in 2007, Li told the then-US ambassador that such data was "man-made".

In March, Chinese customs officials said a single exporter in the northeastern city of Dalian had been found to have over-reported the value of their fake eyelash exports by five times.

Ning's predecessor Wang Baoan was expelled from the Communist Party in January on suspicion of disciplinary violations.