More than 70 percent of American Chamber of Commerce China (AmCham China) companies still plan to increase investment in the country, the organization said Tuesday.

AmCham China released on Tuesday its 16th annual American Business in China White Paper, which reflects the collective views of its more than 1,000 members.

China remains one of the top three investment destinations for American firms, according to the organization.

Over 70 percent of AmCham China member companies still plan to increase investment in the world's second largest economy, but there is a significant drop in those with expansion plans, greater than 10 percent.

Slower economic growth and market access barriers remain the major challenges for American companies in China, said AmCham China, adding that their members hope to see opening of additional service sector industries to foreign investment and China's reform agenda be carried out.

"Slower growth and market access barriers for foreign companies are primary drivers of lower investment," said Greg Gilligan, chairman of AmCham China, at a press conference.

The challenges are becoming more obvious compared to this time last year, and have led to less investment expansion by American market players, Gilligan said.

He added that member companies are encouraged by the Chinese government's ambitious reform agenda and developments such as the China (Shanghai) Pilot Free Trade Zone (FTZ), the Third Plenum Decision and renewed discussion of a bilateral investment treaty between the US and China.

American businesses would like to see a shortened negative list approach and opening of additional service sector to foreign investment, he noted.

The negative list approach means that if a sector is not on the list, foreign companies can invest in it without restriction or joint-venture requirements.

"Many of us believe that current negotiations between the US and China on the Bilateral Investment Treaty are the most important opportunities for improvement in trade relations since China joined the WTO in 2001," said Timothy Stratford, co-chair of the AmCham China Legal Committee.

However, to the disappointment of foreign investors, the negative list is not much different from China's existing lengthy "foreign investment catalog."

A Shanghai official said at the annual Boao Forum on April 11 that the negative list will be further shortened by 40 percent.

The service sector, especially financial and healthcare services, presents great opportunities for American companies, said Kim Woodard, former vice chairman of AmCham China.

In 2013, the service sector accounted for 46 percent of China's economy, compared with 70 to 80 percent in the US, according to AmCham China.

"Market opening and free trade and investment should be reciprocal. The US government pays more attention to what benefits it could reap from the Chinese market rather than what it could share," Bai Ming, a research fellow at Chinese Academy of International Trade and Economic Cooperation, told the Global Times.

The US is expected to ease some restraints on high-technology exports to China. "There is a lot of technology that has a commercial application and a non-military application, so it's in everyone's interest to pursue those," Gilligan told the Global Times on Tuesday.