Jetstar flight attendants were in tears after a loud bang was followed by flames coming from an engine on a Christchurch to Sydney flight, a passenger says.

The Airbus A320 was forced to land with just one engine Tuesday, but Jetstar said no-one was injured and the pilots were completely in control.

Christchurch woman Amanda Tottle, one of 118 passengers aboard flight JQ150, was sitting near the engine when the incident began "with a big loud bang" that shook the plane, the Sydney Morning Herald reported.

She said a nearby passenger told flight a attendants that dark smoke and flames were coming from one of the engines.

"Some of the stewardesses were up the back in tears and kept moving past passengers to look at the engines...and I think that worried some people."

Ms Tottle said passengers were not told what was going on.

A Jetstar spokesman said pilots shut down the damaged engine before safely landing at Sydney Airport.

He denied the engine had been on fire, but said it could have produced smoke.

Passengers were given a "thorough explanation" of the incident, which was coolly and professionally handled.

Jetstar is investigating, while the Australian Transport Safety Bureau is waiting on more information from the airline before deciding whether to launch its own investigation.