One of Australia?s main airport terminals was shut yesterday after 53 people suffered nausea, vomiting, dizziness and respiratory problems, but officials said they could not find the cause of the illnesses. Forty-five people were taken to hospital and hundreds of travellers left stranded when the Virgin Blue domestic terminal in Melbourne was evacuated.

?Our rescue and fire units evacuated the terminal when several people exhibited similar symptoms,? said a spokesman for Airservices Australia. ?What is causing it is simply not known.? Ambulance officials said 53 people fell ill at the terminal and 45 were taken to a hospital decontamination unit. Thirty-five people have since been released from hospital.

Paramedics dressed in head-to-toe protective clothing treated people in a field hospital outside the terminal. Most of the sick were airport workers. Airport officials initially said they believed the cause of the illnesses could be a chemical leak, but fire brigades searched the terminal and found no source for the illnesses. ?We have not found anything. We checked all areas ? the baggage, food preparation, passenger and baggage handling where you would think a chemical might be found,? said a fire official.

?The airconditioning has been turned back on to see if it stabilises. If there is nothing in the air then we will allow Virgin to reoccupy the building,? he said. All departing Virgin Blue flights had been cancelled, while arriving flights were offloaded on the tarmac and passengers taken by bus to another terminal. The nearby Qantas domestic terminal and Melbourne?s international terminal were both operating normally.