WELLINGTON - The Government may face a hill of up to $1 million to clean up the latest border bungle - allowing genetically-engineered (GE) contaminated seeds to enter the country.

Imports of a total of 4420kg of sweetcorn seed is being being investigated for possible GE contamination. About two-thirds of the sweetcorn seed -- 3067.5kg -- was planted in Hawke's Bay, Gisborne, and Ashburton, on about 373ha spread over 25 properties. The bill the Crown faces for cleanup of the latest incident is understood to be in the vicinity of $1 million," Sustainability Council executive director Simon Terry said today.

He said the council had proposed to the Ministry of Agriculture and Forestry (MAF) two years ago low-cost and no-cost biosecurity measures to significantly boost chances of detecting seed contamination and avoiding expensive cleanup bills.

These included trebling the quantity of seeds sampled, to raise the ability to detect low concentrations, and encouraging importers to track and screen seeds for GE content from origin to delivery.

Such quality assurance procedures would aid MAF's stated objective of ensuring New Zealand's GE-free status was maintained. Mr Terry said MAF had put aside the council's proposals, to be reviewed at some later date.

But they would have boosted the chance of detecting GE seeds in the latest shipments, even if the paperwork had not been read correctly at the border.

Green Party co-leader Jeanette Fitizsimons said tonight that efforts by Biosecurity NZ, an agency within MAF, to go back to the US suppliers ofthe seeds, Syngenta, seemed pointless.

"These four consignments came through with documentation that showed GE contamination," she said. "Even if Syngenta provides 100 more documents, it will not change the fact that several tonnes of contaminated seeds have been illegally imported and planted."

Ms Fitzsimons said that for MAF or biosecurity officials to consider letting the corn mature and be harvested, on the condition that it was then exported would send a dangerous signal to markets that expected NZ to be GE-free.

Mr Terry said trying to contain the GE seeds in that way would raise questions about how committed NZ was to the policy of "zero tolerance" of illicit GE seed. "No level of GE contamination is acceptable for the buyers who seek out New Zealand producers because of this country's GE-free reputation," he said.