China released a decade's-worth of information on a key inequality statistic Friday after keeping the measure a secret since 2000, as the issue becomes increasingly sensitive.

The Gini coefficient is a commonly used measure of income inequality, with a figure of 0 representing perfect equality and 1 total inequality. Some academics view 0.40 as a warning line.

China's peaked at 0.491 in 2008 before falling in recent years to 0.474 in 2012, Ma Jiantang, chief of the National Bureau of Statistics, told reporters as he announced readings for the decade from 2003.

The figures "showed the income gap is rather big", he said at a press conference on the country's economic growth.

"These data... reflected the urgency for our country to speed up the reform of the income distribution scheme to narrow the disparity," Ma added, saying the government would work to "better slice and distribute the cake" of China's economic growth.

It was the first time an official Gini coefficient for the country as a whole has been released since the figure for 2000, which the government put at 0.412. Ma said problems reconciling rural and urban components for the statistic were responsible.

China's growing wealth gap is a major concern for the communist authorities, who are keen to avoid public discontent that could lead to social unrest in the country of 1.3 billion people.

Other organisations have published their own readings in the interim, with some sharply higher than the official data.

A survey released last month by a research centre founded by the Southwestern University of Finance and Economics and the Institute of Financial Research, which operates under China's central bank, showed the coefficient at 0.61 in 2010.

That figure would put China at the top of a list of 16 countries by 2010 Gini coefficient on the World Bank website.

Gan Li, director of the research centre involved, declined to comment on the difference with the government's statistics but urged the authorities to take a step further in transparency by disclosing their methodology.

"I'm very happy to see the National Bureau of Statistics publish this data because it has not for the past 12 years," he told AFP.

"I hope the bureau can disclose to the public the whole process of its survey and the original data, so that society can get to know the real situation in China," he added.