US business leaders lashed out on Wednesday at legislation that would penalize companies for employing illegal immigrants.
Presenting its outlook for this year, the US Chamber of Commerce also expressed optimism for the growth prospects of the world's biggest economy, while renewing demands on China to get tough on copyright theft.
Chamber officials had an angry response to an immigration bill passed by the US House of Representatives last month that, among a raft of tough measures, imposes heavy fines on companies found employing illegal workers.
"This is a bill that's going to drag them [illegals] deeper into the shadows," the powerful business federation's vice president Bruce Josten said.
Chamber president Tom Donohue said that the US was a nation built on immigration, and added: "The argument that US companies want cheap labor is crappy."
The House bill, which has yet to be passed by the Senate, also deprived US President George W. Bush of his proposed "guest worker" program, a scheme backed by US businesses that would allow certain illegal immigrants to formalize their status.
Millions of US employers would be required to contact a verification system by telephone or through the Internet to ensure that a job applicant's Social Security number matches with one on file in the databank.
The number of illegal immigrants in the US is estimated conservatively at between eight million and 12 million.
A recent study by the US Congressional Budget Office found that one worker in seven in the US had immigrated, with more than 70 percent of them coming from Mexico and Central America.
On China, Donohue called for the US government to be "very aggressive" about intellectual property rights and encouraged Beijing to open up its currency regime more.
Over the longer term, China must find a way of marrying its political structures to its rapid-fire economic liberalization, Donohue said.