Lindsay Lohan's rehab security 'stepped up over stalker fears'

Security around Hollywood wild child Lindsay Lohan has been stepped over stalker fears, according to reports.

TMZ reported that the actress feared she was being targeted by a stalker after receiving a string of harassing phone calls and text messages from an unknown number.

Lohan is currently undergoing treatment for drug addiction at the Betty Ford Center in Rancho Mirage, California.

Betty Ford Center staff has now beefed up security in order to protect the 'Mean Girls' star following the calls, in which an unidentified person allegedly made disparaging comments about her recovery and her family, reports TMZ.

The anonymous caller also claimed that Lohan was being watched, sources said.

Betty Ford officials responded by moving Lohan to a private facility and limiting her outings, reports the New York Post.