Chinese experts have warned that China is still in a stage where many social conflicts are likely to arise, saying such conflicts are becoming "more varied and complicated."

Land expropriation and housing demolitions, environmental pollution and labor disputes have been the top three causes of mass incidents in recent years, according to a blue book unveiled Tuesday by the China Academy of Social Sciences (CASS).

Conflicts over land expropriation and housing demolitions have given rise to half of the mass incidents, while 30 percent were caused by environmental pollution and labor disputes, according to the blue book.

Mass incidents, which involve a group of people staging a protest, are taking on new features, said Chen Guangjin, vice director of the CASS sociological research center, when he briefed reporters on the blue book on Tuesday.

"China used to see far more mass incidents in the less-developed central and western regions than in the east, but the eastern regions are now witnessing more such incidents compared with the past," Chen said.

"Many of the mass incidents nowadays tend to last for a longer time and are conducted on a larger scale," Chen said.

Salary disputes have caused more than 120 strikes with no less than 100 participants each in the country in the first eight months of this year, figures from the All-China Federation of Trade Unions show.