Most U.S. companies remain optimistic about China's overall economic future, according to the 2010 White Paper on the State of American Business in China issued Monday by the American Chamber of Commerce in China (AmCham-China) in Beijing.

In 2009, amid the fears of a global economic downturn, only 46 percent of American enterprises operating businesses in China said they were optimistic about the country's economy in the year ahead. But this year, the figure dramatically increased to 82 percent.

The medium term also saw the highest level of optimism in three years. More than nine out of 10 survey respondents said they were optimistic about their five-year outlook in China a 10-percent increase over last year's figure.

Now, more American companies are mulling expansions in China, which is one of the top three investment destinations in the world, said Christian Murck, the new president of AmCham-China.

The survey indicates that nearly four of five respondents indicated that their companies would expand their investment in China this year. More than half of respondents (51 percent) said they expected their investment growth to exceed 10 percent.

According to the report, 39 percent of AmCham-China's member companies indicated they were planning to expand to smaller cities, also known as second-tier cities, which demonstrates confidence in the future buying power of Chinese consumers throughout the country.

Despite the optimistic outlook of U.S. companies who took the survey, the report's results indicated that the firms also had growing concerns about certain aspects of China's regulatory environment. Inconsistent regulatory interpretation and the implementation of laws emerged as the top business concern among AmCham-China members.

AmCham-China recommends local governments, especially those in China's western and inland provinces that need the most capital investment, to upgrade their regulatory enforcement and legal structures to ensure a strong business environment for foreign companies.

AmCham-China is a national non-profit organization representing the interests of about 2,600 companies and individuals doing business throughout China. The White Paper is AmCham-China's most important annual policy document. This year, 388 members of AmCham-China participated in the survey, including both small and medium-sized ones and the world's largest multinational corporations.