A consumer protection watchdog has reported a spate of issues relating to Apple iPhones, including exploding batteries and devices unexpectedly shutting down.

The Shanghai China Consumer Association (SCAA) released a report last week detailing eight cases of iPhone 6 handsets catching fire.

The iPhone problems follow the global recall of its competitor, Samsung Galaxy Note 7, with 2.5 million phones returned after numerous reports of exploding batteries.

Apple, however, has denied responsibility for the iPhone 6 battery issue and attributed the fires to external factors.

“There have been some instances that have been brought to our attention by the Shanghai China Consumer Association,” an Apple spokesperson told The New Daily.

Meanwhile, in a statement, Apple said it was in the midst of a “thorough forensic investigation” of the smartphones.

“The units we’ve analysed so far have clearly shown that external physical damage happened to them, which led to the thermal event,” it read.

According to Apple Australia, the issue is only affecting Chinese handsets and there is no record of local users complaining of explosive batteries.

“There are no reports of batteries catching on fire in Australia,” an Apple Australia spokeswoman told The New Daily.

Issues not limited to iPhone 6

Older versions of the iPhone are also reportedly experiencing issues. Photo: Getty

The SCAA also found a number of handsets randomly shut down with around 30 per cent of their battery life still remaining.

The problem, dubbed the ‘30% Bug’, is not limited to the iPhone 6, with reports of older iPhone devices experiencing the issue.

There are no reports of the iPhone 7 or iPhone 7 Plus being affected.

In a message directed to customers on its website, Apple blamed a physical problem for the iPhone battery bug.

“We take every customer concern very seriously, including the limited number of reports of unexpected shutdown with iPhones,” it wrote.

Users of the iPhone 7 are safe, so far. Photo: Getty

“We found that a small number of iPhone 6s devices made in September and October 2015 contained a battery component that was exposed to controlled ambient air longer than it should have been before being assembled into battery packs.

“Some of these shutdowns can occur under normal conditions in order for the iPhone to protect its electronics.”

Apple has since launched a worldwide program to replace affected batteries free of charge.

The statement does not address issues relating to older iPhones.

Apple also plans to release a new version of iOS specifically to diagnose battery performance.

“This will allow us to gather information over the coming weeks, which may potentially help us improve the algorithms used to manage battery performance and shutdown. If such improvements can be made, they will be delivered in future software updates.”