The singer made the decision after realising that her constant partying with Hilton following her split from Kevin Federline was becoming bad for her image. Earlier this week, one of Britney's biggest fansites announced that it was closing down because of her recent behaviour.
A source told the News of the World: "Britney called Paris and said she had decided not to be seen in public with her - she said it wasn't personal. Britney realised her partying was being perceived in a bad light. People began questioning her as a mother."