CHINA'S top think-tank has painted a gloomy picture of the country next year, predicting new friction between central Government and the regions as well as outbreaks of social and ethnic unrest in poor and minority areas. According to a report compiled by the Institute of Sociology under the Chinese Academy of Social Sciences, a new tax system to be introduced next year would change the relationship between the central and regional authorities. This would cause a dramatic change to the mind-set of the people, the experts said, according to the China News Service. ''New friction between the central and local authorities will occur if some problems have not been handled appropriately,'' they said. With the income gap further widening between regions and different social sectors in 1994, the experts said there would be a significant change in public expectations of economic reform and social progress. The possibility of a serious outbreak of unrest in some regions could not be ruled out, they said. The regions and areas with large minority groups, where economic and social development was falling far behind, would be most vulnerable. ''The causes can be a drop of income, worsened social order, strained relations between cadres and the masses, racial disputes, religious conflicts and bad administration,'' they said. ''It is also possible that some accidental incidents might also deteriorate into events with serious consequences.'' The report said that China's crime wave had not been contained despite the high-profile crackdown this year. ''The increase in the floating population, a weak police force and loopholes in the security system will make it extremely difficult for any major improvement in social order next year.'' The experts said ''social evils'' - drug addiction, prostitution and pornography - were likely to remain prevalent next year and even spread in some areas. Arguing that this year's anti-corruption drive would only be intensified with corresponding reforms and legislation, the experts said a failure to push further with the campaign would disappoint the public's high expectations and bring discontent. ''This will in turn undermine the authority of the party and the Government,'' they said. In a list of proposals, the report said the Government should try to maintain the enthusiasm of the regions as it tried to boost tax revenues. The regions should be given preferential policies and autonomy in other areas to compensate for their higher contribution under the new tax formula. ''The central Government should delegate more powers to the regions on one hand, but on the other, maintain stricter supervision [over their use of pow er.] This could become a new experiment over the new form of central-region relationship,'' the reportsaid. The experts also urged the authorities to concentrate on measures to help bridge the gap between rich and poor, saying that this was crucial to social stability and progress. Reform of the social system should also be quickened to keep pace with economic reform. There should be greater supervision of government cadres to help build an efficient and clean administration, they said. The report concluded that a healthy social situation next year depended on stable progress in economic reform, active public attitudes over reform, political stability, and the continued increase of the authority of the central Government. But it pointed out that inflation would stay at a high level in the short run, particularly in large and medium-sized cities. The report also predicted some positive changes. It said ''social and political life'' would become more active as more community groups organised social activities and widened their spectrum of participants.