Samsung Electronics Co on Saturday cited a report by fire investigators as saying an external energy source had caused one of its flagship Galaxy S III smartphones to catch fire in Ireland last month.
The world's top smartphone maker said an investigation by Fire Investigations (UK) had stated that the Samsung device was not responsible for the cause of the fire, and that an "external energy source was responsible for generating the heat".
The new Galaxy S series, the strongest rival for Apple's iPhone, was launched in Europe in late May and in the United States last month.
A Dublin-based consumer posted comments and photos on a web site in June, saying his Galaxy phone had "exploded" while mounted on his car dashboard.
He wrote that while he was driving, "suddenly a white flame, sparks and a bang came out of the phone.
The South Korean electronics giant said it had contracted FI-UK, an independent British provider of consultancy services into fires and explosions, to determine the cause of the fire.
Samsung added it had provided FI-UK with several Galaxy S III phones, including the burnt smartphone, for a series of tests.
"Additionally, the investigation results state, 'The only way it was possible to produce damage similarly to the damage recorded within the owner's damaged device was to place the devices or component parts with a domestic microwave,'" Samsung said on its official global blog .
It also showed the unnamed user's latest comments posted on a web site, saying the phone had been recovered from water and the damage "occurred due to a large amount of external energy" which apparently was used to dry out the device.
"This was not a deliberate act but a stupid mistake," the user added, according to the Samsung blog.
There have been other reports of Samsung smartphones overheating. In March, a Korean schoolboy reported that a spare battery for his Galaxy S II exploded in his back pocket. Samsung said then that the cause was massive external pressure or force.
Heat issues have been reported with other devices. In March, influential consumer watchdog Consumer Reports said Apple's latest iPad tablet threw off a lot more heat than the previous version, lending weight to complaints on Internet forums that the device could get uncomfortably warm after heavy use.