The supply of migrant workers to Chinese cities is drying up, according to a new survey conducted by the Development Research Center of the State Council.

The survey, which covered 2749 villages in 17 provinces and autonomous regions, said in 74 percent of villages there were no longer any workers available who could go and work in distant cities.

Government estimates suggest that around 120 million migrant workers have moved to cities in search of work, and another 80 million are working in small towns.

A report from the Chinese Academy of Social Sciences (CASS) predicts that the Chinese economy now faces an imminent labor shortage. According to the research, labor could be in short supply by 2009 even in the countryside. This is likely to trigger wage rises across the board.

The State Council survey appears to confirm these findings.

Already a labor shortage in some of China's booming cities is putting pressure on wages for certain types of jobs such as construction workers, electricians and skilled technical workers.

The average monthly income of migrant workers was 953 yuan (US$125) in 2006, an increase of 22 percent over 2003.