The kiwifruit growers who banded together to sue the Crown over allowing the bacterial disease Psa-V into the country want to stop the import of mud for Rotorua's Mudtopia festival.

That's because of a recent outbreak of foot and mouth disease in South Korea, where the five tonnes of mud powder is coming from.

Kiwifruit Claim chairman John Cameron said on Saturday that it's just not worth the risk for the Ministry for Primary Industries (MPI) to approve the importation of $90,000 worth of mud.

However, MPI said the mud will be sterile and will not pose any biosecurity risk.

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Some 10kg has already been imported for testing purposes and was cleared by MPI, Rotorua Lakes Council spokesman Henry Weston said on August 3 when queried about the importation of mud powder for the December festival.

"Our primary industries are worth billions to our economy every year," Cameron said in a statement.

"Any outbreak of any diseases could cost people their livelihoods, their farms and jobs and would be devastating to the entire New Zealand economy. Has MPI learnt nothing from the Psa outbreak in New Zealand seven years ago?

"Given that South Korea has recently had an outbreak of foot and mouth, MPI needs to be 100 per cent sure that this mud is disease free – if there is any risk at all of that mud being contaminated with foot and mouth, then the import needs to be stopped."

MPI said the mud will be treated to ensure it is safe.

"MPI is aware of the potential upcoming import of mud from South Korea and we have been working with the Rotorua City Council to ensure that there are no biosecurity risks associated with this shipment," a spokesperson said.

"All imports of risk goods including plants and soil or clay must meet our strict biosecurity standards before being allowed into New Zealand. The product in this case, is clay (but called 'mud') that would be milled and filtered to remove any possible organic material, then heat treated to between 70 and 80 degrees for 72 hours, before being crushed into a fine powder. The mud is finally irradiated at 10 kilogray before it is imported.

"These treatments will make the mud sterile, therefore removing any biosecurity risks.

"To ensure the mud is safe, MPI will verify that the treatments have been applied before providing clearance.

The group says the outbreak of Psa-V in October 2010, which devastated the country's kiwifruit industry, was entirely preventable. It says MPI should never have allowed kiwifruit pollen to be imported.

"MPI has sole responsibility for protecting our borders, and the primary industry sector relies heavily on it carrying out that function to the highest standard," Cameron said.

The High Court trial to hold the Government and MPI to account for the significant losses suffered by growers from the PSA incursion begins in Wellington on Monday. MPI denies all the claims, but the Kiwifruit Claimants say the negligence is obvious.