Britney Spears has been forced to call in the FBI after receiving a string of suspicious packages and letters.

The troubled pop star has apparently been receiving the correspondence for several months, with the letters featuring threatening language and references to Israel and the Middle East.

A source tells E! News, “A lot of it was disturbing stalker kind of stuff. But to be safe her security team is turning it all over to the police and FBI."

LAPD confirmed they “have been looking at allegations that have cropped up in the past couple of months,” although they stated no formal investigation is underway as yet.