The New Zealand Customs Service has issued $70 million in excise duties to several oil companies, which say they won't back down without a fight.
Customs is denying it is imposing a new tax on the oil industry.
Several oil companies are engaged in a standoff with customs over excise duties totalling more than $70 million, dating back to 1986.
Z Energy said it was debating a tax claim with customs and would take legal action if necessary.
BP also said it was considering all options, and Mobil was also involved.
Intermingled fuels that flowed down the pipeline from the refinery at Marsden Point to a huge oil terminal at Wiri in Auckland were at stake.
Z Energy said duty had already been paid on that fuel and the department was seeking a second grab.
Customs officials denied this, though they confirmed they were seeking payment.
But they said it was not an additional excise and could not be regarded as a new tax.
They were not saying more, citing legal reasons.
