Los Angeles: Troubled US actress Lindsay Lohan was sentenced to 30 days behind bars on Thursday after admitting she had violated the terms of her probation for a previous offense.

Judge Stephanie Sautner ordered the 25-year-old to surrender to county jail by November 9 to begin the sentence, while issuing a series of conditions to avoid serving another 270 days behind bars.

Lohan agreed to carry out more community service at the LA morgue and to undergo further psychotherapy sessions -- both of which she had already been ordered to do, but failed to fulfil.

The actress, who arrived wearing a black vintage dress, was ordered to return to court on December 14, after which she must attend roughly monthly court appointments to verify she is fulfilling the terms of the ruling.

"If you do all that, then this jail time (270 days) will be permanently stayed," said the judge, describing her ruling as "putting the keys to the jail in the defendant's pockets."

Lohan was sentenced to 35 days of house arrest in May, as part of a plea bargain over the alleged theft of a USD 2,500 necklace from a jewelry shop near her home in Venice Beach.

Sautner ruled at that time that the starlet had violated her probation for a 2007 drug and drunk driving offense when she allegedly stole the necklace on January 22.

Lohan -- once the promising child star of hit Disney movies "The Parent Trap" and "Freaky Friday" -- has a reputation for hard partying and has faced a series of legal tangles.