A planned maintenance shutdown has hit margins at Marsden Point refinery.
New Zealand Refining Ltd says the week long shutdown affected its ability to upgrade lower cost feedstock into high value products.
The refinery produced 6.9 million barrels and the gross refinery margin stood at $US5.27 per barrel in the two months to August, compared with $US7.07 per barrel with the previous period.
The company earned a processing fee of $30 million.
