Thirty-four Immigration New Zealand staff are being investigated for misconduct, including allegations of fraud and corruption.

This follows the sacking this year of seven immigration staff, three of whom were directly involved in visa processing.

In a response to a written question from Labour in Parliament, Immigration Minister Jonathan Coleman said that on August 16 the department was investigating 32 allegations "concerning conduct and performance" of immigration staff.

Two fresh allegations have emerged since, and Immigration New Zealand says 34 cases are now being investigated.

Eighteen allegations relate to officials in New Zealand, and 16 to staff in branch offices overseas.

The Herald understands that several staff have been stood down, and others have been issued written warnings, but Immigration NZ would not confirm this.

Of the seven officials sacked this year, five were "long-term employees" who had worked at the department between six and eight years.

Labour's immigration spokesman, Pete Hodgson, said it was "concerning" that the department had such a high number of staff facing investigations.

"The question is how long have they been crooked, and how many of the visas have already been inappropriately granted or declined?" Mr Hodgson asked.

Immigration NZ chief Nigel Bickle said it was inappropriate to comment as it might prejudice the investigations.

In the past 12 months, immigration officials faced 60 allegations of fraud, corruption and dishonesty, of which 10 were substantiated, 27 unsubstantiated and 23 were being investigated, Mr Bickle said.

The substantiated allegations related to systems misuse, misconduct and corruption and have resulted in the seven dismissals, four written warnings, one final written warning, one resignation and one suspension.

"The Department of Labour has set very clear expectations about the performance and conduct required of staff, who have been provided with training in the code of conduct and are reminded regularly of the importance that is placed on the integrity of the immigration system," Mr Bickle said.

"It is obviously disappointing that some staff have been dismissed for misconduct."

Mr Bickle said the department investigated all allegations that were made.

A colleague of a staff member under investigation for system misuse said the agency was "acting on every tiny complaint" in recent months, and this was affecting morale.

"People make allegations when decisions don't go their way, and it's really a waste of time and resources when every one is being investigated," said the officer.

"There seems to be more of a 'big brother' culture now at Immigration and some of us just feel like we're being watched a lot more."

He did not want to be identified because he said speaking to the media without authority could result in criminal charges, formal warning or immediate dismissal.