UPDATED 4.21PM: All New Zealand flights are now back to normal following a brief suspension in operations this afternoon.

Airways New Zealand reported there was an internal network failure about 2.15pm.

A fault in the radar system has seen all New Zealand flights grounded.

Airways New Zealand is now reporting operations have now resumed and they expect to resume full service by 4.30pm.

"We apologise for the inconvenience caused."

We suspended flights while we investigated the issue, satisfied we could operate safely. At no point was safety of airport ops compromised

— Airways New Zealand (@AirwaysNZ) June 23, 2015

Earlier:

All commerical flights have been grounded after a fault in the national radar system was discovered. Flights currently up in the air can land but no planes are allowed to take off, Radio New Zealand reported, reports Stuff.co.nz.

Auckland Airport said Airways, which controls New Zealand's air space, had identified a national fault and was trying to fix it, RNZ said.

Air NZ's arrivals and departures schedule for Tauranga shows another seven flights set to arrive from either Christchurch, Auckland or Wellington and four to depart the city.

Airways Corporation, which runs the national radar system for all flights, was "experiencing an issue with its system across the country".

The fault was affecting all commercial departures across the country.

"The company is working to resolve the issue as quickly as possible," Christchurch Airport said in a statement.

An Auckland Airport spokesman said they were notified of the fault at 2.50pm Tuesday. Wellington Airport general communications manager Greg Thomas confirmed the grounding.

At 2.48pm today 23/6/15 we experienced a radar failure. We are working on the issue, and will provide an update.

— Airways New Zealand (@AirwaysNZ) June 23, 2015

rtpt We are holding all aircraft on the ground, however those in the air will be cleared to land.

— Airways New Zealand (@AirwaysNZ) June 23, 2015

One theory behind the fault is a severe geomagnetic storm that the Spaceweather.com website reports is currently in progress.

The geomagnetic storm follows a series of rapid-fire coronal mass ejection strikes to Earth's magnetic field in the last 24 hours.

Magnetic fields in the wake of the latest CME are strongly coupled to the Earth's own magnetic field.

This is a condition that could sustain the geomagnetic storm for many hours to come.

A sunspot currently facing earth has erupted.

X-ray and UV radiation from the flare ionized the upper layers of the Earth's atmosphere, producing a moderately-strong blackout of shortwave and low-frequency radio signals.