A major worldwide tech outage, believed to have been triggered by a flawed anti-viral update from US cybersecurity company CrowdStrike, has caused chaos among many of the world’s largest companies and disrupted the retail, banking and aviation sector in New Zealand.

The outage has affected some of the biggest companies globally, including banks, IT firms, and airports, resulting in grounded flights.

It is understood that a flawed update was rolled out globally, locking companies out of their computer systems.

People fueling up their cars this evening have been advised to use cash.

A spokeswoman for Z Energy acknowledged the problems with contactless card and online payments.

“At this stage, Z Energy’s (Z) backup offline payment systems appear to be working on most occasions, and customers can continue to pay with cash or their Z Business Fuel card,” the spokeswoman said.

“We are continuing to investigate the issue and seek updates from our third-party suppliers.”

The global IT outage has affected Christchurch Airport.

A number of the company’s systems may affect flight arrivals and departures the company said.

The airport is urging passengers to check with airlines before travelling to the airport.