The spotlight has once again fallen on the cargo of the missing Malaysia Airlines Flight MH370 after authorities today confirmed the aircraft was carrying lithium-ion batteries which can be highly flammable.

The confirmation by MAS chief executive officer Ahmad Jauhari Yahya today comes just four days after he denied the aircraft was carrying any hazardous goods and instead highlighted the "three to four tonnes of mangosteen" on the plane.

"We carried some lithium-ion small batteries, they are not big batteries and they are basically approved under the ICAO (The International Civil Aviation Organisation) under dangerous goods.

"It is not dangerous goods per se but in terms of... they are not declared as a dangerous good under ICAO, so we packed as recommended by ICAO," he told a daily briefing on the search of MH370 at Sama-Sama Hotel, KL International Airport.

Jauhari insisted the lithium-ion battery cargo was checked “several times” to ensure it was packed in accordance with ICAO guidelines.

“Airlines do that all the time, it is not just Malaysia Airlines. These goods are being flown by many airlines as cargo anyway, (which) is based on ICAO’s ruling,” he added.

According to the US-based Federal Aviation Administration (FAA), a total of 141 air incidents involving batteries carried as cargo or baggage were recorded between March 20, 1991 until Feb 17 this year.

‘Battery fires caused crashes before’

In rare cases, entire aircraft have been destroyed as a result of fires started from lithium-ion batteries, with the most recent cases being Asiana Airlines Flight 991 and UPS Airlines Flight 6, though both incidences involved cargo aircraft.

In the case of UPS Airlines Flight 6 which took off from Dubai to Cologne, Germany, it crashed after attempting an emergency landing at Dubai International Airport on Sept 3, 2010, killing the crew members.

The United Arab Emirates’ General Civil Aviation Authority, in a 322-page report of the incident published in 2013, concluded that the crash was linked to fire started by lithium-ion batteries in the cargo.

The report said the pilot had to leave his seat in search for portable oxygen on the smoke-filled flight deck after which the Boeing 747-400F lost communication.

“It is possible that a lithium-type battery or batteries, for reasons which cannot be established, went into an energetic failure characterised by thermal runaway and auto ignited, starting a chain reaction which spread to the available combustible material,” the report said.

Following such concerns, the ICAO last year imposed a new rule requiring any shipment containing more than two lithium-ion batteries to comply with a detailed hazardous goods requirement.

‘Possibility overlooked’

The possibility of fire as a result of lithium-ion batteries that led to the loss of Flight MH370 was first raised by CNN on Mach 14, but little attention was paid to it as authorities declined to reveal the content of the plane’s cargo.

Flight MH370 on the KL-Beijing route lost communication with traffic control on March 8 at 1.30am over the Gulf of Thailand.

The plane’s loss triggered a massive search in the South China Sea, but it was revealed by military data that the plane had made a turn-back and flew into the vast unknown.

Investigators have established that the aircraft’s last-known location to be somewhere between the borders of Kazakhstan and Turkmenistan to the northern Thai border, or from Indonesia to the southern Indian Ocean.

However, after 14 days of a multinational search involving 26 countries, the plane had yet to be found.