Vodafone New Zealand, the country's biggest mobile phone operator, has appointed expatriate Mark Aue as its new chief financial officer, replacing Adolfo de la Fuente who is returning to Spanish arm of the global telecommunications group.

Aue starts with the local Vodafone unit next month after spending several years in the UK in finance roles with Vodafone Group and its global enterprise unit, a spokeswoman said in an emailed statement. De la Feunte recently left the New Zealand arm of the global group, ending his assignment and returning to Vodafone Spain. He ceased being a director of Vodafone New Zealand and its subsidiary Vodafone Mobile NZ on Nov. 30, according to documents filed with the Companies Office.

Vodafone has been contending with shrinking mobile customer numbers, which dipped below 2.3 million as at Sept. 30 in an increasingly competitive market.

It acquired the TelstraClear fixed line business in October 2012, which it anticipated would help it reduce its reliance on telecommunications wholesaler Chorus with the network's backhaul and transmission services, while reaping cost savings by cutting back-office duplication.

The Auckland-based company posted its first annual loss since 2000 in the 2014 financial year, with finance costs relating to the acquisition weighing on the bottom line and offsetting revenue gains from the enlarged business.