Lindsay Lohan's father claims he knows who her drug dealer is.

Michael Lohan - who has alleged his actress daughter is addicted to prescription drugs - believes the 'Mean Girls' star is being targeted by a man who is aware of her reliance on legal substances.

He told website RadarOnline: "This guy follows Lindsay all over the place. All over. Lindsay pays for him to go everywhere. He has no job. He does nothing. All he does is supply everyone in Los Angeles."

Michael - who has a history of drug abuse himself - recently vowed to help Lindsay beat her addiction.

He said: "I'm going to get her off the prescription drugs that she's on. I hate it when people talk about illegal drug abuse because it's not just drinking and illegal drugs that kill you.

"Prescription drugs can destroy and kill a person and are sometimes harder to stop. Look at Heath Ledger and Michael Jackson."

Although he refused to say what medications his 22-year-old daughter is taking, he admitted her addiction has taken over her life.

He said: "You know why Lindsay's not acting in feature films right now? Because she can't. Because the girl with all the talent is hidden and buried deep inside this fungus that's grown because of the prescription drugs. She can't be herself.

"When you hug her she's vacant inside. When she kisses or holds me I get chills, and not in a good way - in a bad way."

Lindsay, 21, has previously completed three stints in rehab in a bid to get help for her addiction to drink and drugs.