Qantas rat plane to fly again on Thursday

Qantas had some extra passengers hitching a ride. (Getty)

Qantas had some extra passengers hitching a ride. (Getty)

Qantas is investigating how five rats got on board an aircraft that had to be grounded in Sydney on Tuesday.

Qantas is investigating how five rats got on board an aircraft that had to be grounded in Sydney on Tuesday.

Flight attendants found the rats on the Boeing 767 10 minutes before passengers were due to board a flight to Brisbane on Tuesday afternoon, a spokeswoman said.

The rodents, which were discovered in a storage compartment, were "baby rats", she told AAP on Thursday.

"We are currently investigating how they got into the aircraft," she said.

Passengers who were due to board the flight were transferred to another aircraft, while staff killed the rats and searched the cabin to ensure there were no more inside.

Engineers who inspected the plane on Wednesday found no damage had been caused to the plane's wiring systems.

The aircraft was due to return to service on Thursday morning, the spokeswoman said.