Beijing will release its own version of a closely watched international inequality index, state media reported Sunday, becoming the first Chinese city to announce such a plan.

The official Xinhua news agency, citing a spokesman for the National Bureau of Statistics Beijing survey branch, said the city would release a Gini coefficient for 2012.

The figure will be published "in a timely manner", spokesman Xing Zhihong told a press conference Sunday.

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.

China on Friday released a decade's-worth of Gini coefficients for the country as a whole after keeping the data under wraps since 2000.

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, said Friday as he announced readings for the decade from 2003.

The figures "showed the income gap is rather big", he told a press conference on the nation'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.