Robbie's stalker

Robbie Williams is under attack.

The U.K. pop star has called the police about a female stalker, Music 365 reports.

The 45-year-old woman, Valentina Semenenko, has been sending him strange letters and calling him since they met at a counselling group for drug users.

Robbie is a recovering drug addict and offered his friendship to his stalker when they met at Narcotics Anonymous in Notting Hill, but the friendship took a nasty turn.

Valentina has been sending Robbie written notes that read:

"Give me some respect, this is not a game, I need someone and so do you" and "Don't turn your back on me."

Robbie's mom, Jan, answered a few calls from the stalker, who immediately sent off another note that read:

"You used your mother to lie to me. I'll be 'round at 7 a.m. tomorrow."

After Valentina started calling Robbie at his home in Notting Hill, the singer decided to go to the police.

Police sources told the U.K. tabloid Sunday People that the obsessed Robbie fan thinks the two share a special relationship.

"She found out where he lived, which is around the corner from her, and then bombarded him with a series of letters and phone calls," the source said. "But it was when she started turning up on his door step demanding to see him that it got too much for Robbie. He gave a full statement to police and an officer will be paying her a visit. But there is not a lot more police can do at this stage, she hasn't broken any law."

--AllPop