Lindsay Lohan's 17-year-old sister is the only person who can save her.

The troubled 'Mean Girls' star has been to rehab three times and after she was spotted partying with heiress Paris Hilton recently, her father Michael Lohan has claimed her younger sibling Ali is the key to helping her recovery.

Michael told RadarOnline: "I'm so worried about the people around my daughter; she continues to surround herself with people that are going to hurt her.

"It's sad and very scary what is happening to Lindsay. I just what her to get it right."

"Ali is literally the only person I know that can help her. Right now all she needs is her family. Her mother Dina, siblings Michael, Cody, Ali and I are the only ones that can help her stay sober. She needs to come home literally and metaphorically. Dina and I are in a much better place to support her in her sobriety."

While Michael would love if his 25-year-old daughter attended university with her younger sister, he believes she needs to go back to rehab first.

He added: "Maybe Lindsay should go to college with Ali.

"What will it take for her to listen? Jail is not the right place for her, but she needs to go to a rehab that understands her problems. She has been to some of the worst rehabs in the country. Just because they have a name doesn't mean can help her."