The world's busiest airport - Hartsfield Jackson International - is suffering a power outage that is reportedly delaying flights.

The outage is causing flight delays, according to the Atlanta Journal-Constitution.

The Federal Aviation Administration has set a ground stop in Alanta due to the outage which means all flights in the state are being held at departure airports.

No flights from New Zealand fly direct to Hartsfield Jackson International but it is an important transit airport for Kiwis travelling around the US.