The US Department of Transportation (DoT) has introduced new rules on carrying lithium batteries on planes.

Tighter regulations mean that lithium batteries carried as spares will now be limited to two per passenger.

Any extra batteries must be stored in plastic bags or the original packaging as checked-in luggage.

"Doing something as simple as keeping a spare battery in its original retail packaging or a plastic zip-lock bag will prevent unintentional short-circuiting and fires," said Krista Edwards, deputy administrator of the DoT Pipeline and Hazardous Materials Safety Administration.

Edwards added that existing fire control systems in aircraft would not be able to cope if non-rechargeable lithium batteries caught fire.

Lynne Osmus, assistant administrator for security and hazardous materials at the Federal Aviation Administration, claimed that the new rules will protect passengers.

"It is one more step for safety. It is the right thing to do and the right time to do it," she said.

The move ends a bad year for lithium batteries. Millions of units have been recalled and some airlines have banned certain models of laptop from being used during flights.