The socialite was booked into the Clark County Detention Center on the cocaine charge, Las Vegas police spokesman Marcus Martin said.
The 29-year-old Hilton was in a car driven by a friend that was stopped when officers noticed what they suspected to be marijuana smoke coming from it, he told The Associated Press.
"Officers noticed a vehicle leaving smoke trail of a controlled substance (and) made a stop based on that," Martin said.
During the stop, officers found what appeared to be a drug on Hilton and later tests showed that it was cocaine, Martin said. He didn't know how much was found.
He said Hilton was apparently recognized by passers-by and a crowd quickly gathered in the area where the vehicle had been pulled over.
Police watch commander Lt. Wayne Holman said Hilton was still being held around 2 a.m. Saturday but would probably be freed on her own recognizance later in the morning.
Hilton's manager didn't immediately return AP calls for comment early Saturday. Her publicist, Dawn Miller, did not immediately return an e-mail message.
Polices didn't release the name of the man who was driving the car. Martin said he's not sure if he was also arrested.
Hilton was arrested this summer after the Brazil-Netherlands World Cup match in Port Elizabeth, South Africa, on suspicion of possession of marijuana. The case was then dropped at a midnight court hearing.
Hilton also pleaded no contest in 2007 to alcohol-related reckless driving and was sentenced to 45 days in jail.
After spending about 23 days in jail, Hilton told US
television host Larry King that the experience caused her to re-evaluate the role partying played in her life. She said she wanted "to help raise money for kids and for breast cancer and multiple sclerosis." While most famous for her tabloid exploits and reality TV series "The Simple Life," Hilton has appeared in the films "Bottoms Up," "The Hottie and amp; the Nottie" and "House of Wax."
