Hollywood wild child Lindsay Lohan is being treated for cocaine addiction at the Betty Ford Clinic, RadarOnline.com has exclusively learned.

"Lindsay's primary problem is cocaine," said a source, close to the situation.

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"She went through a thorough assessment, and it was discovered that she has a high dependence for cocaine."

The Mean Girls star, who has been to rehab five times and was jailed three times for cocaine related incidents, had previously played down the extent of her drug abuse.

Lindsay Lohan's jail stay may be much longer than is expected, RadarOnline.com has learned exclusively.

Her probation will be formally revoked on Friday, RadarOnline.com has learned but once that happens she may have to go behind bars and wait for a probation violation hearing to be held, a source close to the situation told us.

Los Angeles Superior Court Judge Elden Fox will formally revoke LiLo's probation, and then schedule the probation violation hearing. A source close to the situation told RadarOnline.com: "Lindsay could be remanded directly into custody on Friday, pending the probation violation hearing, and it's very likely that Judge Fox will do that.