BEIJING - A top Chinese statistician said Wednesday the country's Gini coefficient, an index reflecting the rich-poor gap, in urban and rural areas has been distorted and does not paint a true picture of equality in the world's second-largest economy.

Ma Jiantang, director of the National Bureau of Statistics (NBS), made the remarks during a panel discussion with political advisors on the survey about China's residential income.

Ma said the NBS does not intentionally hide the Gini index from the public, but is unable to produce genuine data according to the current survey methods.

According to Ma, the Gini coefficient for China's rural areas stood at 0.3897 last year, close to the alarming level of 0.4 set by the United Nations.

Meanwhile, the Gini index was 0.33 for urban areas.

"To be honest, both the Gini indexes (for rural and urban areas) are lower than their actual levels," Ma said, noting that the surveys on China's residential income are carried out separately, using different indicators.

The statistician said that in separate surveys, the NBS collected data on the disposable income for urban residents through a household book-keeping process, while gathering figures on net income for rural residents.

"As the basic data are separate, we can't calculate a uniform Gini coefficient for the country," Ma said, adding that the reluctance of high-income urban households to record their incomes on the books made conducting the surveys very difficult.

He noted the NBS will only publish the Gini index after it can use the same survey method and choose the samples according to the same indicators to collect data from urban and rural households.

Ma said the NBS is considering using housing prices as a key reference to revise the data on high-income households' incomes.