Lindsay Lohan allegedly drank alcohol at the Coachella Valley Music and Arts Festival on Saturday.
The 27-year-old actress, who vowed to stay sober at the event at the Empire Polo Club in Indio, California after recently confessing to having "one glass of wine" since leaving rehab for the sixth time last summer, has been accused of consuming vodka with a group of friends, including her sister Aliana, 20, during Kid Cudi's set.
An eyewitness allegedly told InTouchWeekly.com: "She looked completely out of it. She couldn't stand up straight and she was frantically chain-smoking cigarettes. In one of her hands she had a plastic cup with a clear liquid in it.
"The group was standing in a small cabana, booth type thing and one of the friends was making regular trips to the bar. I overheard the friend order four vodka sodas and when he carried them back to the group. He handed one to Lindsay and she started drinking it. She didn't seem to care who saw and none of the group seemed concerned."
The 'Canyons' star's brother Michael recently admitted on her OWN reality series, 'Lindsay,' that he was worried about her sobriety.
He said: "My biggest worry is for a relapse. It scares me, it scares my family to death. This time I really hope is different. I just want her to be happy."
But sources close to the actress insisted last week that Lindsay was doing well and hadn't had a drink since her first slip-up.