A team of anonymous hackers has claimed a $1 million (£648,000) bounty for remotely jailbreaking Apple's latest mobile operating system, iOS9.

Jailbreaking is the practice of removing Apple's restrictions on their devices, allowing users to install a range of unauthorised apps and tweaks on their phones and tablets.

Jailbreaking is often done willingly by people looking to customise their device, but since it bypasses the security restrictions, jailbreaking can also be a technique used by hackers to break into phones and install spyware.

The hefty prize was offered by cybersecurity company Zerodium, who offered $1 million to any person or team who could come up with a browser-based untethered jailbreak for iOS9 in September this year.

The conditions of the competition required that the hacking process "should be achieveable remotely, reliably, silently and without requiring any user interaction except visiting a web page or reading a SMS/MMS."

In other words, the winning team found a way to remotely install an app on phones running iOS9 simply by getting the the user to open a certain webpage or read a text message.

The terms required that the break-in would have to be truly remote - any solutions that involved the iPhone being plugged in to a computer, or being accessed through Bluetooth or NFC did not qualify.