Britney Spears has been put on high alert after receiving a series of disturbing letters and packages, according to U.S. reports. The Toxic star's security teams has handed the correspondence, which contains information about bomb making, to police and FBI agents. While Los Angeles Police Department officials have yet to launch an investigation into the weird mail, spokesperson Ana Aguirre confirms, "We have been looking at allegations that have cropped up in the past couple of months."