Adding to its recent spate of safety scares and impending strikes, Qantas has been confronted with a new problem – rats in the cabin.

Staff discovered five baby rats in the cabin of a Boeing 767 jet shortly before customers were due to board.

The airline said it was a rare occurrence and passengers, who were due to fly from Sydney to Brisbane, were put on another plane while the rodents were disposed of.

A Qantas spokeswoman said engineers checked the plane after the discovery and found the rats had done no damage.

“We don’t know how they got there. The aircraft was at the gate for some time before departure and we are investigating,” she told AFP.

“It is a rare occurrence. We have no record of it ever happening before.”

Qantas is going through a torrid period. It has recently warned that profits would be hurt by the recent natural disasters in Japan, New Zealand and Australia. And this week its CEO accused pilots of threatening the future of the Australian flag carrier. Alan Joyce said he refused to give in to “outrageous” pay demands of pilots, who are poised to take their first strike action in 45 years following the collapse of negotiations.

Last November the airline’s impeccable safety record was blemished after one of its superjumbos made an emergency landing after experiencing engine trouble shortly after taking off from Singapore on its way to Sydney last November.

The airline grounded all six of its fleet of Airbus A380 airliners to carry out safety inspections. It has also suffered a series of more minor safety scares this year.