The Earthquake Commission (EQC) says its investigation into invoices for earthquake repairs in Canterbury has revealed instances of possible contractor fraud which it will refer to police.
EQC chief executive Ian Simpson told Morning Report the commission is in discussions with people about 2000 invoices, although that does not mean those are all suspect.
He says there are some genuine mistakes, including invoices submitted for work, such as safety inspections, which is not covered.
"But there are some in there where the contractor is claiming for work that the homeowner says wasn't done, or they appear to be charging us $200 an hour for labour rates, or they're charging for materials that don't seem to have been used."
Some contractors have complained that they have waited months for the commission to pay bills for hundreds of thousands of dollars. The Amalgamated Workers Union has said it will take legal action over unpaid invoices.
Mr Simpson says most contractors are being paid by the 20th of the month after invoices are received.
He says contractors providing detailed and accurate invoices to the commission are being paid in a timely manner and the organisation won't be railroaded into paying invoices which need to be checked more carefully.
Mr Simpson says the Commission has paid out $4 million to settle overdue accounts since mid-May, while invoices for another $3 million are under review.