Emma Watson was terrified when her alleged stalker approached her on set.
The 22-year-old actress was filming in Long Island, New York when a trespasser on the set tried to hand her a note but the horrified star screamed as she recognised him as someone who had previously been following her.
A source told the Daily Mirror newspaper: ''The man managed to slip on to the set with some visitors and then approached her.
''She recognised him from hanging around outside her house and screamed.
''He took off into the woods and was chased by security and a couple of the tough stunt guys who also happen to be martial arts fighters.
''They caught up with him in the woods. Police were called and he was removed. It was really creepy.''
Emma was said to have been so devastated, she had to take some time to calm down.
The insider added: ''Emma was really shaken up and was given some time to compose herself.''
The man was warned about trespassing but not charged.