Business groups have warned the federal government against tightening the 457 visa scheme for temporary overseas workers.

Immigration Minister Brendan O'Connor said on Saturday the 457 visas will be changed to ensure that they are only used to address genuine skills shortages and that local workers are getting a "fair go".

But the resource industry employer group, the Australian Mines and Metals Association (AMMA), says the government should take a cautious approach to making any changes.

AMMA chief executive Steve Knott said the overseas skilled migration program played a small but critically important role in the resource industry.

"With $650 billion worth of resource projects proposed for our country, it is an absolute fact that our industry cannot source all the skilled people it needs domestically," Mr Knott said in a statement on Sunday.

He urged the government not to make it more costly or complex for employers to access the 457 visa.

Mr Knott also disputed claims that hiring overseas workers was a cheap option for employers, pointing out that it costs up to $60,000 more per person in the resource industry.

Australian Industry Group chief executive Innes Willox said the 457 program was an economic shock absorber and should have the flexibility to meet rises and falls in demand.

He added that the program needed freeing up and not further tightening.

"Employers will always prefer to hire locally but we still don't have the right skills in the right places and employers have been forced to turn to immigration programs to supplement their local workforce," he said.