Three people arrested over the seizure of $17 million worth of methamphetamine allegedly imported to New Zealand by the Bandidos motorcycle gang have pleaded guilty to a series of charges.

Queenie Anne Matthews, 59 and Meinata Piahana, 29, on Monday pleaded guilty to three charges each of importing or attempting to import packages of P into Auckland in late 2015 and early 2016.

Further, more serious charges they originally faced would be dropped, the High Court at Auckland was told.

Co-accused Adrian Le'Ca, 56, entered guilty pleas to importation in 2016, possessing 14.9kg of methamphetamine, and 1.9kg of cocaine.

Five other charges against him have been dismissed.

The trio will be sentenced on November 10.

At the time of the arrests in October, 2016, police said about 17kg of methamphetamine, $150,000 of jewellery and $200,000 cash had been seized in a seven-month operation with Customs.

They alleged the drugs had been imported by a member of the Thailand chapter of the international Bandidos gang.

A trial for the group - along with a fourth woman whose single money laundering charge is expected to be dropped - had been set to start on Monday.