Daniel Radcliffe being protected by four ex-SAS bodyguards

Harry Potter pin-up Daniel Radcliffe is being protected by four ex-SAS bodyguards after receiving a horrifying death threat from a stalker, it has been claimed.

The actor, 18, was so shaken up by the threat -- he switched cars three times on Saturday night during filming of the seventh and final installment of the Potter franchise, The Deathly Hallows.

And his regular driver -- used by the star for seven years and considered "part of the family" -- has been suspended until further notice.

The nature of the threat, received via Warner Bros, is unclear - but it is being treated seriously.

A source said: "There is a real concern for Daniel’s welfare. The bigwigs haven’t said what has been going on. It’s all hush-hush — but security has been massively ramped up."

According to British newspaper The Sun, the protection Daniel is receiving is similar to that given to princes William and Harry when they are not on military duty. Daniel has also been given a "chase car" -- which follows the vehicle in which he is traveling in case of emergency.

The weekend car switches took place during night-time location filming in Farnham, Surrey.

The source said of the SAS guards: "They are all experts in evasive driving, threat assessment and close protection. This isn’t about keeping an eye out for the paparazzi — these guys are looking for something far more sinister.

"Daniel has the four guards with him at all times, as well as a new driver. When he travels they use dummy cars and swap vehicles."