Flight comparison site Kayak shows the average price of a return flight from Auckland to Wellington peaked at $400 at the end of May.
It claims return flights from Auckland to Christchurch in April were six times higher than February.
Commercial regions manager Mike Williams says the average fare for Auckland to Christchurch has only increased 13 percent from February, when physical distancing was not required.
There was no increase to the Auckland to Wellington fare.
Williams says it's not aware of any formal investigation by the Commerce Commission.