THE US Government says laptop and other electronic devices should not be carried in cargo holds on aircraft.

They say they are less of a fire threat if they are transported in the passenger cabin.

The Federal Aviation Administration said: "Devices containing lithium metal or lithium ion batteries (laptops, smartphones, tablets, etc.) should be transported in carry-on baggage and not placed in checked baggage."

The primary reason laptops are safer in the passenger cabin is because the flight crew or passengers at least have a chance to put out a fire if one is sparked by the batteries in an electronic device.

Many major airlines now carry pioneering AvSax bags which will contain the threat quickly. They have already been deployed 14 times this year to deal with fires in electronic devices caused by lithium-ion batteries.

The move does not mean that airlines are banning passengers from put ting their electronics in checked bags.

But if they are packed in bags that will go in the cargo hold of flights they "should be completely powered down to the off position (they should not be left in sleep mode), protected from accidental activation, and packed so they are protected from damage."

The advisory backs up a complaint issued by many in the airline industry after the Department of Homeland Security issued tighter security rules for certain flights from the Middle East to the USA earlier this year.

Those rules, which have since been modified, banned passengers from having electronic devices larger than a cell phone in their carry-on bags. At the time, Homeland Security was acting on intelligence that indicated terrorists may try to hide an explosive in an electronic device or use several devices to detonate a bomb.

As soon as that rule went into effect in March, safety advocates warned of the potential risk of lithium-ion batteries igniting in a checked bag and sparking a larger, uncontrollable fire in the cargo hold that could bring down a commercial airplane.

That concern prompted the Fire Safety Branch of the FAA to conduct tests looking at the potential hazards of putting laptop computers and other electronic devices in checked bags.

Its conclusion was clear: large electronics are safer in the passenger cabin than in the cargo hold.

In late June, the USA modified its security protocol for all international flights, requiring enhanced security ranging from tighter screening to the use of new, more advanced, carry-on bag screeners that can more easily detect a potential bomb.

Since then, several airlines say they have enhanced security and have announced the TSA has approved their procedures.

AvSax are now on board several major US carriers.

The AvSax is a special fire-retardant bag used when lithium-ion batteries in mobile phones or other electronic devices catch fire.

Simply pour at least two litres of water into an AvSax and then drop the burning device into the bag. The water activates the polymer gel inside the bag causing it to expand around the device. Should the device keep on venting then the AvSax is tough enough to absorb the force.

In short, the AvSax cools the batteries in the device, reducing the likelihood of the battery catching fire but if it does go into what is known as thermal runaway it is all contained within the bag.