WELLINGTON - All commercial and civilian aircraft in New Zealand were temporarily grounded yesterday,when a fault crippled the nation's air traffic control system, causing long delays and some flight cancellations.

Airways New Zealand, which manages air traffic control in the country, said all flights, including international and domestic services, were affected. The government agency insisted no planes or passengers were in danger during the outage, which lasted more than two hours and left air traffic controllers without any radar.

As a result, all flights were banned from taking off, said the Civil Aviation Authority (CAA), and those already in the air were guided down using "visual manual separation" - that is, eyesight and radio contact.

Airways NZ blamed the problem on "an internal network failure".

"Airways immediately suspended all flights while we investigated the issue and until we could be satisfied that we could operate safely," it said. "We have now identified the issue and thoroughly tested the integrity of the system."

Transport Minister Simon Bridges said air traffic controllers communicated with flights via radio during the radar outage. He stressed that there was "absolutely no compromise to the safety of passengers or planes".

But the CAA said it was concerned about the incident and had launched a safety investigation.

A CAA spokesman said he was unaware of any similar failures in the past and it was being treated seriously. Asked whether such a scare was unacceptable to the travelling public, he responded: "Absolutely."

Local media reported that close to 200 flights were affected, with long delays and some cancellations at airports around the country.

Airways NZ's website says it manages 30 million sq km of airspace, handling about one million aircraft movements annually.

"Airways NZ apologises to all passengers who have been affected by this outage," it said in a statement.

AGENCE FRANCE-PRESSE