Video footage of an iPhone allegedly exploding in a young man's pocket has been posted online.

17-year-old Henri Helminen is seen pulling out the violently smoking device from his pocket and throwing it on the floor, in security tape footage acquired by Finnish news siteKauppalehti.

"The phone was working perfectly" beforehand, Helminen told Kauppalehti. The unidentified iPhone model bought no more than three months ago was destroyed in the fiery incident, he added.

Apple did not respond to request for comment on Wednesday.

Authenticating the video is nigh on impossible. However, it's not the first time iPhone users have reported their shiny rectangles self-immolating.

In 2011, one Australian airline reported an iPhone 4 glowing red and emitting thick smoke as a plane landed in Sydney, according to The Telegraph. The case was referred to the Australian Transport Safety Bureau (ATSB) for investigation.

In a follow-up report, the safety regulator said there had been "no previous record in the ATSB's databases of self-ignition involving mobile telephones or other portable electronic devices" on aircraft in the country, and the incident was a result of a "misplaced screw" in the device thought to have been from a shoddy repair job.

A week later, another iPhone 4 "spontaneously combusted" in Brazil. As it happened on dry land, there was no official investigation into the cause of the incident.

Samsung has also seen its flagship Galaxy S III smartphone in the news under similar circumstances when a report of a recently released Android device "burned from the inside out" after the owner connected it to a non-charging car mount.

Photos posted on an Irish message board showed the device's underside had melted around the charging point.

Samsung acknowledged the board postings and signaled an investigation would be carried out. "We are committed to providing our customers with the safest products possible and are looking at this seriously," a statement read.