On the contrary, a strengthening of the New Zealand dollar against the United States greenback since last week would have eased import costs.
BP spokesman Jonty Mills acknowledged that the currency had strengthened, but said international fuel prices remained too volatile yesterday for his company to absorb the tax rise.
"We had another look this morning - the international commodity prices are still very volatile but we'll keep looking at those." He said the four latest price rises - from 196.9c in late June - followed seven consecutive decreases since mid-May, from 219.9c.
Excise duty on petrol rose yesterday to 50.524c a litre, the first increase for two years, pushing the total tax take to 88.899c. That includes an ACC levy of 9.9c and GST of 27.77c.
The oil firms at least absorbed a GST increase of 0.26c on the excise rise.
LEVIES ADD UP
Main centre petrol price (91-octane) - 212.9c a litre
Includes
* Fuel excise - 50.524c
* GST - 27.77c
* ACC levy - 9.9c
* Local authorities fuel tax - 0.66c
* Petroleum monitoring levy - 0.045c
* Total tax - 88.899c.