Medical authorities in Australia treated 22 passengers on Thursday for a mystery gastric illness after they became ill on a Qantas Airways Ltd flight from Chile, Qantas said. Several ambulances and medical staff met the aircraft after it touched down in Sydney. Those affected, who media said had been vomiting, were given medical treatment on board. "A number of passengers travelling in the same group on QF28 from Santiago to Sydney became unwell with a gastro intestinal illness," Qantas said. "It is believed the illness was contracted before boarding the aircraft and symptoms became evident during the flight." The airline said the flight's pilots and crew were not affected by the illness, and other passengers were processed through customs. However, all passengers were advised to keep watch on their health, and to seek medical advice if they become ill over the next two days, according to a report of Reuters.