Immigration New Zealand is looking to outsource more immigration applications, despite fraudulent student visas being issued out of its Beijing office and claims its Palmerston North student visa branch is a ''rubber stamp factory''.

The Government last month revealed 279 fraudulent student visas had been issued through its Beijing office and said Immigration NZ staff were being investigated for possible links to the fraud.

In an anonymous letter to Labour's industrial relations spokeswoman Darien Fenton, a staffer claimed the majority of those Chinese students have now been issued further student visas from the Palmerston North student branch.

''Palmerston North student visa branch is a 'factory' where visas are rubber stamped.''

Immigration NZ had approved 35,000 applications under its Student Online system run from Palmerston North.

Immigration Minister Nathan Guy last month told a select committee the Government wanted to process more applications centrally.

''We'll look to outsource some of these lower-level applications with third parties. We'll look to increase online access - currently working very well with our student visas in Palmerston North, where they are processing half of those in a turnaround of about 48 hours.''

Fenton said further outsourcing was a ''huge worry''.

There were questions around offshore and onshore visa processing, and Immigration NZ was distracted with being restructured into the new Ministry of Business, Innovation and Employment, she said.

''And the minister is now saying he is going to make it less face-to-face and more online processing and contracting out.''

NZ First leader Winston Peters has called for an investigation into VFS Global Services, a company contracted by Immigration NZ to process visa applications in China.

Guy said New Zealand had a robust immigration system and no evidence of systemic fraud had been uncovered at any other branches.

Immigration NZ head Steve Stuart said more online processing of applications would go ahead despite the Beijing fraud after the Government invested $75 million in the new Immigration Global Management System.

Immigration NZ would continue to use VFS Global Services because it had nothing to do with the fraudulent activity uncovered in Beijing.

"They are a service provider who simply receive applications and are not involved in the decision making process around visas."

- © Fairfax NZ News