Apple is investigating a report by an Arizona teen that her iPhone 7 Plus "blew up" as it was charging and began spewing smoke.

"We are in touch with the customer and looking into it," an Apple representative told Mashable, which first reported the news.

The customer, Brianna Olivas, posted a video on Twitter on Wednesday showing her rose-gold iPhone 7 Plus with a melted case smouldering on a bathroom counter.

"So my IPhone 7 plus blew up this morning... was not even using it, literally no explanation for this," she wrote.

Images shared online of the melted iPhone 7. (Twitter)

For now, there's no evidence that the charred remains of this particular iPhone 7 are anything but an isolated incident, although in spring an Australian man reported a similar incident with the smartphone.

Apple did not respond to a request for further information on Friday.

Last year, Samsung took a major financial hit after its high-end Galaxy Note 7 smartphone turned out to be at risk for catching fire or even exploding because of a battery design flaw.

The company issued a recall but its replacement units had the same issue. Samsung was forced to kill off the device, which the company said would result in losses of more than US$5 ($6.5) billion.