SYDNEY — More than 20 passengers who became ill during a Qantas flight from Chile to Australia were treated by paramedics and placed in quarantine Thursday on arrival at Sydney airport, the airline said.

The sick passengers were part of the same tour group and were suspected to have contracted their gastro intestinal illness before they boarded the 14-hour flight in Santiago, Qantas said.

The Boeing 747 was met by ambulance paramedics who treated the sick passengers in quarantine, Qantas spokesman Luke Enright said.

The New South Wales state Health Ministry said in a statement that the 26 passengers developed vomiting and diarrhea consistent with norovirus infection, a common cause of outbreaks of gastroenteritis in Australia and elsewhere.

Paramedics were assessing the sick passengers, all Australian residents. Passengers well enough to leave were to be escorted through the airport with minimal exposure to other passengers, the ministry said.

Enright could not say when the flight crew became aware of the sickness on board. It was not an emergency that could have resulted in the flight being diverted, he said.

"They've known for some time in the air that sickness was aboard so they were able to call through and organize for the appropriate authorities to greet the aircraft at the arrival, and those passengers were quarantined," Enright said.

The ill passengers were moved to seats at the rear of the plane near where four toilets were located, Australian Associated Press reported. Enright confirmed that the passengers were seated near the rear, but could not say whether they had been moved there by the cabin crew.

Qantas said other passengers were advised to keep a close eye on their health over the next two days and to seek medical advice if they feel ill.

Enright declined to say how many passengers were on the flight. AAP reported that more than 300 passengers were aboard, without citing a source.