'Chemical leak' puts 50 in hospital

Over 50 people were hospitalised following what is believed to be a chemical leak at Melbourne Airport, report agencies.

Hundreds of people were evacuated from the airport following several incidents of nausea and vomiting, dizziness, headaches and respiratory problems, mostly among security and airline staff working in the departure area for Virgin Blue, a domestic carrier.

The entire domestic terminal was subsequently evacuated as security staff and firefighters tried to trace the source of the toxic fumes.

'Initially, when we got the first reports, there was immediate testing done of the air quality and the airconditioning systems and nothing was identified through that that could have caused the problem,' Melbourne Airport spokeswoman Brooke Lord was quoted as saying.

"But as we got further reports of people feeling unwell, as a precaution, the aviation rescue and firefighting (crews) working on site decided to evacuate the terminal."

Several flights were cancelled or delayed.

Melbourne airport fire service spokesman Brett Smiley told journalists the source of the leak had not yet been identified and that the terminal would remain closed indefinitely.