The "Frozen" hit maker has beefed up her security after the threats during her ongoing 'Sticky & Sweet' world tour and arrived in Belgrade, Serbia, in disguise to perform her concert in front of 30,000 fans Monday, reports contactmusic.com .

The star took extra precautions after receiving threatening messages from Balkan fanatics, hiring a posse of bodyguards to protect her as she took the stage in the Serbian capital for the first time.

The worried singer will also be accompanied by the stepped up security in neighbouring Romania, where she is set to play a gig Wednesday.

source: TOI