A source told website RadarOnline.com: "Lindsay and her co-conspirator were forced to give it up and flag down a volunteer, who was crossing the centre's grounds on a golf cart.

"The pair were safely returned, decaffeinated, to their hall, where they were the centre of a process meeting over what they had done."

Lindsay Lohan, who will be in court Friday for alleged failed drug tests, leaves a friend's house in West Hollywood holding onto a long white object and a pack of Parliament cigarettes.

There is no soda dispenser at the clinic, which forbids luxuries such as caffeine and television."

As well as Lindsay being banned from getting her caffeine drink fix, it was recently claimed staff have urged her to cut down on her use of social networking websites and email.

A source said: "Lindsay is only allowed to use her phone for two hours a day, and only to keep in touch with family and close friends.

Lindsay Lohan wears an oversized grey jumper for dinner with her brother and friends. Lohan has reportedly admitted failing drugs tests just weeks after being released from jail. The "Herbie" actress could face jail after allegedly violating the terms of her probation.

"Before, she would repeatedly and compulsively email her friends if she was ever in a situation where she felt lonely, and she would vent on twitter."

The policy has been implemented so Lindsay can "concentrate on herself" during therapy.

Lindsay is due in court on October 22 for a probation hearing, following her failed drugs tests.

The 'Mean Girls' actress - who served 13 days of a 90-day jail term behind bars in July for breaching the terms of probation set for a 2007 driving under the influence (DUI) conviction - returned to prison following the failed tests, but ended up spending just a matter of hours behind bars after posting $300,000 bail.