Snakes, spiders, cane toads and frogs are among the more than 400 pests, on average, slipping past New Zealand's biosecurity checks every year.
Information released to Radio New Zealand News shows that last year, more than 300 pests got past the border. However, the ministry says about 3,500 pest animals were seized.
The Ministry of Agriculture and Forestry says a third of live lizards and snakes brought into the country make it through border checks, often arriving in luggage brought through airports.
Pests also make it through the border in fresh produce, machinery parts and used vehicles on shipping containers. However, MAF spokesperson Paul Bingham says the risk of the creatures establishing themselves in this country are low.
Federated Farmers and Forest and Bird say biosecurity should be tightened and better resourced because the breaches threaten the country's economy and ecosystems.
Federated Farmers biosecurity spokesperson John Hartnell says given that 64% of New Zealand's total income comes from agriculture, forestry and aquaculture, the ramifications of some pests making it into the country are massive.
Horticulture New Zealand's chief executive, Peter Silcock, says further checks at the point of origin must be carried out.
The ministry says although not every piece of cargo can be physically checked, the breaches are not acceptable. MAF Biosecurity director of cargo clearance Jeremy Lambert told Morning Report the agency wants to bolster existing checks at the point of origin.
He says the ministry has 10 offshore programmes for cleaing sea containers and used cars and inspecting fresh produce from the point of origin.
Job losses not a factor - ministry
The Ministry of Agriculture and Forestry says job losses last year did not compromise its biosecurity controls.
The lobby group Forest and Bird says job cuts happened at completely the wrong time, but MAF says the positions were cut because the recession caused a decline in the number of used cars coming into the country.
The ministry also queries claims that 50 jobs were lost, saying this proposal was whittled down to 20 positions in the end.
But the main public sector union is not convinced. The Public Service Association says staff are stretched very hard, dealing with more than 170,000 goods and passenger movements a day.
It says last year's job cuts were based on expectations that this would diminish due the recession, but it did not happen for passenger movements, and the fall-off in cargo volumes has started to reverse.