New Zealand Post has more than doubled its half-year profit, but says that doesn't mean it has "turned the corner".

Net profit of $35.4 million for the six months to December 31 was up $19.6 million from $15.8 million earned in the same period last year.

However, chief executive Brian Roche says the pleasing improvement was not a case of turning the corner.

"New Zealand Post faces the challenge of operating in a flat economic environment with residual effects of the Christchurch earthquake and the ongoing uncertainty in the global economy."

There was still an urgent need to pursue to keep up with plans for a sustainable postal network. This includes growing its subsidiary Kiwibank, creating new digital offerings and keeping the store network fresh.

NZ Post's courier and logistics business made the biggest contribution to revenue, which rose $27.2 to $679.7 million compared to the same time last year.

The traditional postal business was still seeing a decline as New Zealanders posted 29.4 million(or 7%) fewer letters domestically over the period.

New Zealand Post will pay an interim dividend of $2.5 million, compared to $1.8 million last year.