The draining and excavation required to extract the logs was destroying fragile wetlands and dune lakes, she said.
Northland MP Winston Peters yesterday added his voice to calls for a moratorium on the trade. He called for a full investigation into what authorities had done, or failed to do, to police an industry that was "quite clearly avoiding the rules".
The trade was not in New Zealand's interests and was a tragedy for wetlands that were being drained. Mr Peters conceded the trade created jobs, but said they were few in number and would not last long.
"This is not an industry we should be applauding. It is creating wealth for a few, plundering our environment and making a mockery of our laws," he said.
Green MP Eugenie Sage also called for a inquiry and accused the Government of failing to enforce the Forests Act.
"MPI's failure to uphold and enforce the law means that ancient wetlands are being plundered and swamp kauri logs that are tens of thousands of years old are being carted off overseas. There are only a finite number of these ancient logs in Northland and once they are mined and exported, they are gone forever," Ms Sage said.
Mr Guy said the export of kauri logs as Maori carvings was closely monitored.
"I have seen photos where some fantastic-looking kauri swamp logs have been carved, and they are going to be an amazing feature for our country ... So we manage it very, very closely," he said.
Swamp kauri may be exported as a finished or manufactured product, or a personal effect. Whole or sawn stumps or roots may be exported with a milling statement and export approval, but logs may not be exported, either whole or sawn.