Ambulance officers assessed the passengers, who complained of nausea and headaches, during the Brisbane to Mackay flight.

Four cabin crew were also checked after they reported feeling off-colour.

Flight JQ882, with 182 passengers on aboard, landed after 8am this morning.

The passengers, who were not sitting in the same area, reported to cabin crew that they were smelling a strange odour, and started feeling light-headed and nauseous, said Jetstar spokesman Simon Westaway.

Their complaints were passed on to the pilot who made an announcement asking if there were any doctors on board.

Fortunately for the ill passengers, there were two, who monitored the passengers ahead of the landing.

The pilot radioed for emergency services to be ready upon landing, and fire trucks and ambulances were awaiting the plane’s arrival on the tarmac.

The six passengers required no treatment and no one was transported to hospital, a Queensland Ambulance Service spokeswoman said.

Mr Westaway said it remained "bit of a mystery" as to what might have caused the passengers to feel unwell.

Firefighters and engineers were inspecting the plane, an Airbus A320, which has been taken out of service.

There was some 'chlorine-like' odour detected, but its source remains unknown, Mr Westaway said.

While technical staff continue to examine the plane, Jetstar's service between Mackay and Brisbane remains disrupted.

Any spare capacity on Qantas link or Virgin Blue would be secured to help people get to their destinations, but some customers might have to be put up overnight if the plane remains out of service, Mr Westaway said.