Dozens of Qantas passengers sick at Sydney Airport

Several students have spent the night in hospital after being struck down with a gastro bug during a Qantas flight from Chile to Sydney.

Around 26 people became ill, several hours into the 14-hour flight, suffering diarrhea and vomiting.

Sixteen of the sick passengers, believed to be Melbourne students, were taken to hospital. Three had to be stretchered from the aircraft.

More than 300 passengers were on the flight when it left Santiago around midnight (AEST) on Thursday.

About three hours into QF28, members of the tour group began vomiting.

It is understood they were students returning from the international Catholic event, World Youth Day, in Rio de Janeiro.

A fleet of six ambulances was sent to help, with paramedics boarding the aircraft in Sydney, around six o'clock last night.

The Health Department believes passengers contacted a norovirus infection.

"[It is] a common cause of outbreaks of gastroenteritis in Australia and elsewhere," according to a statement released by NSW Health last night.

"[We have] provided Qantas with a letter and factsheet about viral gastro to distribute to all departing passengers, as well as advice for cleaning and cabin staff."

Qantas believes passengers contracted the illness before boarding.

Paramedics board Qantas flight QF28 at Sydney Airport. Photo: 7News
Paramedics board Qantas flight QF28 at Sydney Airport. Photo: 7News