Lithium-ion batteries are pictured at the production site of Saft Groupe, battery specialists, in Poitiers, France, October 5, 2017. REUTERS/Regis Duvignau

BERLIN (Reuters) - European aviation safety authorities have urged airlines to remind passengers about how best to transport electronic devices containing lithium ion batteries over the busy Christmas travel period.

Lithium ion batteries, found in devices such as laptops, mobile phones, tablets, and electronic cigarettes, are seen as a fire risk, and there are concerns that if a fire were to start in the hold of a plane, it could not easily be extinguished.

“It is important that airlines inform their passengers that large personal electronic devices should be carried in the passenger cabin whenever possible,” the European Aviation Safety Agency (EASA) said in a statement on Tuesday.

Many airlines in Europe already have their own procedures in place, such as telling passengers that laptops should not be carried in hold baggage.

EASA said that where such items are too large to be carried in the cabin, then they must be completely switched off, protected from accidental activation, and packaged suitably to avoid damage. They should also not be carried in the same bag as flammable items such as perfume or aerosols.

EASA also said that if devices cannot be carried in the cabin, such as when passengers have to put carry-on bags in the hold due to a lack of space in the cabin, airlines should remember to ask passengers to remove any spare batteries or e-cigarettes.

Lithium ion batteries are also used to power so-called smart bags, suitcases which offer GPS tracking and can charge devices, weigh themselves or be locked remotely using mobile phones.