Another discount fuel chain arrives in Christchurch this week when Waitomo opens its first outlet in the city on Thursday.

The unmanned station, on a former sales yard site at the corner of Fitzgerald Ave and Tuam St, will be the first in the South Island for Waitomo.

The family-owned business is based in the King Country and has more than 65 North Island outlets. It buys wholesale fuel through an agreement with Mobil and has been able to extend south by gaining access to Mobil's Lyttelton and Woolston fuel terminals.

ALDEN WILLIAMS/STUFF The new Waitomo petrol station on the corner of Fitzgerald Ave and Tuam St.

Christchurch already has both manned and unmanned stations run by Nelson-based discount chain NPD. Gull, owned by Caltex Australia, is planning to open the first of several fuel stops in the city on Ferry Rd, Woolston.

Waitomo has been in the Wellington market since May, where the cost of unleaded fuel this week was about 20 cents a litre lower than its major brand competitors, according to petrol price app Gaspy.

In Christchurch this week, the cheapest petrol price was $2.04 at NPD on Stanmore Rd.