Samsung on Saturday cited a report by fire investigators as saying an external energy source had caused one of its flagship Galaxy S III smart phones to catch fire in Ireland last month.

A user in Ireland last month posted online images of Samsung's flaghip Galaxy S3 smartphone that appeared to have severe burns on the bottom of the device. Samsung responded to the incident and on Saturday by contracted Fire Investigations UK (FIUK), an independent third-party organization, to determine the exact cause of the damage, which had allegedly been affected by heat.

The damaged device and additionally provided devices were examined and exposed to a series to tests. The investigation summary states that "The energy source responsible for generating the heat has been determined as external to the device" and "the device was not responsible for the cause of the fire."

Additionally, the investigation results state, "The only way it was possible to produce damage similar to the damage recorded within the owner's damaged device was to place the devices or component parts within a domestic microwave."

Additionally, the device user in Ireland that had posted online the images of the burnt smartphone admitted that he was responsible for the damage.

"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 smart phones 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.