PHOTOS: #ISIS threatens to attack Prince George in his nursery school in London

ISIS-supporting extremists have threatened to attack Prince George at his London school, warning, 'Even the royal family will not be left alone', it has been claimed.

The extremists allegedly posted the message alongside a photo of the future king entering his Battersea school on Telegram, an encrypted instant messaging app.

The message included the address of the £18,000-a-year Thomas's Battersea, saying 'school starts early'.

It also featured a message in Arabic taken from a jihadi song, which translate as: 'When war comes with the melody of bullets, we descend on disbelief, desiring retaliation.'

An investigation by the Daily Star uncovered the messages on Telegraph, which British spies are now monitoring around-the-clock to prevent potential ISIS attacks.

Residents living near Prince George's school, as well as parents of other students, had raised concerns about security at Thomas's Battersea ahead of Prince George starting classes last month.