Australian health authorities are closely monitoring passengers who flew on a commercial flight in which a passenger with tuberculosis was accidentally allowed onboard.

An investigation is underway and authorities have already admitted the man should never have been allowed on the June 11 Qantas flight from Cairns, Australia, to the Torres Strait, the Australian Associated Press reported.

"This has been a major breakdown in our normal processes and procedures for the transport of patients between facilities," Cairns and Hinterland Health Service district chief executive Julie Hartley-Jones told the AAP.

Doctors said the risk to passengers and crew was minimal.

"Short-term, one-off exposure, such as a two-hour flight, is not generally sufficient to result in any infection," Cairns Base Hospital director of thoracic medicine Dr. Graham Simpson said.

"Most people who become infected have experienced exposure to TB over a prolonged period of time."

Click here to read more from AAP.