The biggest US business group in China complained Tuesday that "humiliating" American visa requirements are driving Chinese business customers away from the United States.

"US visa policies inhibit our Chinese customers from travelling to the United States to buy US goods and services," he added.

"Nearly half of our member companies believe that they have lost significant sales opportunities due to visa problems for PRC (People's Republic of China) citizens."

The report complained that "our understaffed consular missions and cumbersome visa process" drive potential Chinese customers away to rival companies in Europe and Japan.

Chinese clients, including many representing major state-owned companies, reported to Amcham that the US visa process was "lengthy, uncertain and personally humiliating".

The report urged the US government "to develop a more coherent, coordinated and robust US export promotion strategy to capture a greater share of China's sizeable and growing market".

Echoing Chinese government demands, AmCham-China also appealed to Washington to relax export controls in sectors such as high technology to boost the amount of US goods heading to China.

An overwhelming majority of US companies surveyed in the 171-page report -- 91 percent -- said they were either "optimistic" or "cautiously optimistic" about China's economic outlook over the next five years.