Justin Bieber is reviewing security measures at his new California home after finding two teenage fans trespassing on the estate while he was hosting a pool party last month (Jan15).

Reports suggest one of the girls was celebrating her 12th birthday when she was caught trying to take photos of her pop idol and his friends.

The Baby singer spotted the two trespassers and berated them, confiscating one of their cellphones.

Tmz.com reports the singer chose not to involve the police and simply told the girls to leave his property.