A little-known visa category facing accusations of systematic abuse needs to be urgently safeguarded by Immigration Minister Peter Dutton, the Labor Party has said, expressing concern that subclass 400 visas are being used as a "back door" to undermine the government's foreign labour crackdown.

The call for action follows a recent Fairfax Media report that detailed how the 400 visa – designed to parachute international specialists into short-term roles – has emerged as a "sleeper" category with looser restrictions than the high-profile 457 visa.

"Peter Dutton needs to make sure 400 visas aren't being used to get around skills shortage lists, bypass genuine labour market testing or undercut local wages and conditions," opposition immigration spokesman Shayne Neumann told Fairfax Media.

"Labor has genuine concerns that 400 visas are being used as a back door to bypass the Turnbull government's own skilled migration rules. Loopholes in our visa system undermine the integrity of Australia's skilled migration program and impacts local workers trying to get a job."