Up to 300 million Chinese farmers will move into cities over the next 20 years, said a report released by the United Nations Development Program (UNDP).

China is experiencing the world largest urbanization movement. Fast economic growth is driving the process, said the report.

The report, carried out by Chinese Academy of Social Sciences, predicted that, by 2010, there will be about 125 cities in China with a population of over one million. Fifty cities will have a population in excess of two million.

Despite fast economic growth since the 1980s, the contribution of Chinese city clusters to the national economy is lower than in developed countries.

Cities are still growing at breakneck pace and their production efficiency is low. What's more, the high population density in Chinese cities creates problems for sustainable development, said the report.

City cluster development should be included in the national strategy and a national system should be set up, according to the report.

China has over 1.3 billion people and more than 800 million are farmers.