Energy Minister David Parker yesterday afternoon said the Economic Development Ministry would next month invite tenders for additional stock, which could be crude oil or refined products such as petrol and diesel.

New Zealand’s current stocks are about 60 days of net oil imports.

The additional stock required to meet the 90-day target is estimated at 418,000 tonnes this year, 302,000t in 2008, nil in 2009 and 32,000t in 2010.

Parker said the quantities required to meet the target were significantly lower than earlier estimates because of expected increases in domestic oil production from next year, principally from the offshore Taranaki Pohokura and Kupe gas-condensate fields, and the Tui Area and Maari oil fields.

Additional stock might be held in New Zealand or in Australia, the US, the UK, or The Netherlands, subject to government-to-government arrangements.

Any stock held in Europe or the US could be swapped with stock held in Australia to reduce transport costs should the stock be required in New Zealand for a local emergency.

However, most stock would need to be held overseas for the next few years, since New Zealand currently had little spare storage capacity, Parker said.

The government would also meet the costs of acquiring the additional reserves, estimated to be about $NZ50 million ($A42 million) over the next three years, to avoid the need to impose further levies on petrol and diesel sales, according to Parker.

Subject to a successful tender round and the finalisation of government-to-government arrangements, New Zealand expected to achieve the IEA target by the end of this year.