Apple has confirmed an Intel glitch has affected all iPhones, iPads and Mac computers.

The US tech giant said the processor flaw, known as Meltdown and Spectre, could leave millions of customers exposed to security vulnerabilities.

It emerged this week that developers have been trying to prevent hackers taking advantage of the flaw in microprocessors built by Intel and ARM.

There has been no evidence so far the flaws have been exploited by hackers.

However, they are causing devices to slow down by up to 50% when performing particular tasks, including large spreadsheets and graphing applications.

In a blog post, Apple said it had released software updates for iOS, its phone and tablets software, macOS, used by its computers, and tvOS for its television products.

It said the AppleWatch is not affected by Spectre.

Users should only download apps from trusted sources to avoid being made vulnerable, the post said.

"Security researchers have recently uncovered security issues known by two names, Meltdown and Spectre," Apple added.

"These issues apply to all modern processors and affect nearly all computing devices and operating systems.

"All Mac systems and iOS devices are affected, but there are no known exploits impacting customers at this time.

"Since exploiting many of these issues requires a malicious app to be loaded on your Mac or iOS device, we recommend downloading software only from trusted sources such as the App Store."

Apple said it will release an update for its web browser, Safari, in the next few days.