An Australian woman told Monday how she was horrified to discover live maggots in a snack she was eating while on a Qantas flight from Los Angeles to Melbourne.

Victoria Cleven began tucking into her snack of nuts and dried fruit as she made her way home on Thursday. At the time, she did not turn on her overhead light as the cabin was darkened.

"It tasted strange, and I turned the light on and looked at the rest of the packet, and just started seeing maggots coming out of it everywhere," Cleven, 42, told Melbourne's Herald-Sun newspaper.

"I couldn't talk. I was nearly throwing up. I was beside myself."

Her 15-year-old son then checked two other packets of the snack and found they also were seething with maggots.

Qantas said it had apologised to the woman and would investigate how the situation arose.

"We've apologised to her for her experience," a Qantas spokesman told AFP.

"We're speaking to the supplier of the trail mix to try to establish how it could have happened.

"We're taking it very seriously," the spokesman added.