The troubled saga of actress Lindsay Lohan took another dangerous turn early on Tuesday when police charged her with drunken driving and cocaine possession after a frightened woman dialed authorities to report being chased by Lohan's sport utility vehicle.

Less than two weeks out of rehab, with another drunk driving case pending, Lohan had a blood-alcohol level of between .12 and .13 per cent when police found her about 1:30 am (0830 GMT), Sgt Shane Talbot said.

Authorities had received an emergency call from the mother of Lohan's former personal assistant, said Officer Alex Padilla. The assistant had just quit hours before, he said.

"The mother was afraid," Padilla said. "She wasn't quite sure what was going on so she called the police saying she wanted to make sure everything was going to be OK."

The woman apparently did not realize it was Lohan who was behind her, Padilla said.

Police said the woman drove her black Cadillac Escalade into the parking lot of Santa Monica's Civic Auditorium, about a block away from the Santa Monica Police Department, followed by Lohan driving a Denali sport utility vehicle.

Misdemeanor charges

Authorities arrived and saw Lohan and the woman in "heated debate," Padilla said. Lohan and the woman each had two passengers in their vehicles, Padilla said.

After a field sobriety test, the 21-year-old movie star was booked on two misdemeanor charges of suspicion of driving under the influence and driving on a suspended license and two felony charges of possession of cocaine and transport of a narcotic, Talbot said.

During a pre-booking search, police found cocaine in one of Lohan's pants pockets, Talbot said. Several hours later, Lohan was released on $25,000 bail.

A call to Lohan's publicist, Leslie Sloan Zelnik, and attorney, Blair Berk, were not immediately returned. Padilla said he did not know why Lohan was trying to catch the woman, whom he did not name.

Last week, Lohan turned herself in to Beverly Hills police to face charges of driving under the influence in connection with a May hit-and-run crash.

In January, Lohan also had checked into rehab for substance abuse treatment.