The MED secured the contracts through a global tender, ensuring New Zealand holds the minimum oil stocks equivalent to 90 days of the previous year's net imports - one of the main obligations of belonging to the Paris-headquartered IEA.

The additional oil reserves are held under 'ticket' contracts, which provide the government with the option to purchase petroleum in the event of an IEA-declared emergency, so as to minimise the effects of such a disruption on New Zealand.

The tickets for 285,000 tonnes of crude oil, petrol and diesel for 2008 were secured for $US5 million ($A4.3 million), the ministry said.

It added that this was the first year New Zealand had completed a contract for stocks in Japan, following the signing of a bilateral treaty with Japan last month.

The MED also said that increased domestic liquids production from Taranaki - following the start of gas and condensate production from the near-shore Pohokura project in late 2006, and the more recent crude oil flows from the Tui Area development had reduced the amount of reserves the Government needed to hold.

New Zealand's total 90 days obligation for 2007 was 1.4 million tonnes and for 2008 will be 1.2 million tonnes.

Depending on the timing of new crude-condensate production - with the Maari crude oil development due to come onstream in mid-2008 - a tender might be required for stocks in 2009.

But with the Kupe gas-condensate project due to come onstream by mid-2009, no additional reserves might be necessary for 2010, the MED added.