Immigration Minister Brendan O'Connor announced one of his first acts since being handed the portfolio would be to tighten the Australian 457 visa regime's regulations, claiming there was widespread abuse of the system, a practice known as 'rorting'.

The 457 visa program is intended to allow Australian employers to bring in overseas workers, but only when local labour is not available. The federal government however, along with several workers' unions, contends that employers are exaggerating the skills needed in order to pass or subvert local labour checks and bring in overseas workers.

Mr O'Connor has used rising rates of 457 visa approvals against relatively steady employment rates over the Australian summer as proof that the system needs better restrictions.

"These January figures show that after the traditional December lull, 457s have continued to increase," said the minister.

"At January 31, there were more than 105,000 people in Australia working on temporary 457 visas. That is an increase of 22.4% to January 2012.

"That says to me that there are now more 457 applications coming where there are not demonstrable skill shortages."

However, Mr O'Connor's federal counterpart, the opposition's immigration spokesperson Scott Morrison, has contradicted the immigration minister, citing a lack of any official report of the 'rorting' being used to justify the clampdown.

"To suggest there are rorts because more visas have been handed out is like suggesting there is a drought because the sun is shining," said Mr Morrison. "One is not evidence of the other."

"All I have called for in the wake of the government's announcement is to produce the report of the inquiry or the investigation conducted by the department (of immigration) that demonstrates the widespread rorting and abuse that the claims, and that is absent."

The opposition, led by Tony Abbott, has accused Prime Minister Julia Gillard of using the 457 issue as an attempt to win conservative voters disappointed at the government's inability to address the asylum seeker issue.

"I'm worried that Julia Gillard's targeting these workers...as a smokescreen because of her failings on the border protection front," said opposition foreign affairs spokeswoman Julie Bishop.

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The Australian Visa Bureau is an independent migration consultancy specialising in helping people lodge applications with the Australian Embassy.