The Cook Islands audit office is investigating a complaint about the New Zealand foreign minister Murray McCully and his 58-strong delegation which toured the Pacific last month.
The audit director Paul Allsworth says his office has received a complaint alleging the delegation, in the Cook Islands as part of a Rugby World Cup Pacific tour, didn't pay departure tax.
People leaving the Cook Islands, including residents, are obliged to pay a 55 New Zealand dollars departure tax.
Mr Allsworth says the amount involved is more than 3,000 dollars.
His office is reviewing the process through which departure tax exemptions may have been granted for Mr McCully's delegation, and an audit brief on the matter is to be completed this week.