The PSP was in the boy's trouser pocket at the time and while the unit wasn't turned on, it began to heat-up rapidly, according to various reports.

The boy was treated for second-degree burns on his leg.

While Sony was in hot water last year with numerous instances of laptop computer batteries overheating and even catching fire, this is the first report of a PSP battery burning up.

A Sony spokesperson told a US publication that it was investigating the case, including the possibility that the faulty battery could have been a cloned and unauthorised model made by a third-party manufacturer.