Katie Melua is living in fear after papers detailing her every move for the rest of the year were put up for sale on the Internet.
According to The Sun the breach of her security turned even worse when a man who has stalked her joined the auction.
The papers list the teenage singer's gigs, which airports she will be flying from, flight details - and even which hotels she will stay at.
A friend of Katie's said: "These sensitive documents will cause her a lot of trouble if they get into the wrong hands.
"Katie loves performing and meeting her fans. But she's a young, attractive, single woman and it's not a good idea for exact details of her whereabouts to be available for sale on the Internet. Katie won't be able to sleep at night knowing there could be people lurking around outside."
The seller - known only as bandro1186 - claims to have found the extensive schedules backstage at Guilfest 2004 in Guildford, Surrey, on Saturday last week. They have been put on auction site eBay to try to make as much money as possible from Katie's fans.
Katie has sold more albums in the UK this year than any other artists. Debut Call Off The Search has shifted more than 1.2million copies, going quadruple platinum.
Katie's management got particularly worried last night when it became clear the obsessed fan had been persistently bidding big money for the documents.
The bundle appeared on eBay two days ago - and has already attracted a load of bids up to £200.
The listing states: "I found this at Guilfest in the VIP bar behind the main stage. It is genuine and does tell you where she is going to be for the rest of the year. When her live appearances are, where she's flying to and what airports."
