(Cover) - EN Showbiz - Lindsay Lohan celebrated her sister's birthday with "champagne" and fine food.

The actress' little sister Aliana Lohan turned 18 today.

To honour Aliana's official entry into adulthood, Lindsay hosted an intimate get-together with mother Dina, younger brothers Michael Jr and Cody, and friends at Beaumarchais restaurant in New York City Wednesday night.

Michael Jr was also celebrating his birthday and the group seemed to get along swimmingly.

"It's clear Lindsay and Michael Jr are very close," an eyewitness told Life & Style magazine. "They were talking a lot and Michael had his arm around her at one point. She seemed to be confiding in him."

Partygoers ordered from a prix fixe menu that included truffle gnocchi and tuna tartare. Alcohol was flowing at the table.

"Lindsay ordered a bunch of glasses of champagne for the table and switched to drinking that," the source explained.

Lindsay escaped for a cigarette break with her mom before dessert.

The star then snapped photographs with sister Aliana before asking the staff to prepare a cake and champagne sparklers for their table.

"The staff brought out cake and two brownie sundaes while everyone sang [Happy Birthday]," the witness went on. "Lindsay toasted with champagne."

Although there has been controversy surrounding Aliana's thin frame in recent months, witnesses assure that the model ate a hearty meal.

"[Aliana] had a lot of bread, a big salad and a bunch of her brownie sundae," the source said.

Lindsay and Aliana's father Michael Lohan was not in attendance. (C) Cover Media