Lindsay Lohan's hot secret sister

Lindsay Lohan has a secret half-sister, it has been revealed.

The 'Mean Girls' actress' dad Michael fathered a daughter while he was still married, although estranged at the time from Lindsay's mother Dina.

Speaking about the relationship over 13 years ago, Michael - who has three other children, Michael, Ali and Cody, with Dina - told America's OK! magazine: "Years later the woman contacted me, convincing me that I was the only person she was with and that she had my child."

Michael - who married Dina in 1985 before they divorced in 2007 - has even written letters to the girl's mother saying his illegitimate daughter "is beginning to look a lot like Linds, with a mix of Cody, believe it or not".

He also sent his daughter a photograph of himself, which he signed 'Love Daddy'.

The girl's mother says that while Michael called his daughter on her 13th birthday in June and has had many conversations with her, he has never visited her or provided financial support.

She said: "It's time for Michael to take responsibility."