Paris Hilton was summoned to appear in court today and faces being sent back to jail after her early release provoked outrage and allegations of favouritism.

The socialite was freed from a Los Angeles County jail yesterday morning and allowed to spend the rest of her sentence at home, amid fears that she was on the brink of a nervous breakdown. The 26-year-old hotel heiress who has made a career out of being empty-headed, had served fewer than five days of the 45-day prison term given to her by courts.

The decision to allow her to go home was condemned as an example of “double standards” by the Rev Al Sharpton, the black civil rights campaigner.

“This early release gives all of the appearances of economic and racial favouritism that is constantly cited by poor people and people of colour,” he said. “There are any number of cases of people who handle being incarcerated badly and even have health conditions that are not released.”

The decision to release her early was made by the sheriff on undisclosed medical grounds. “I can’t talk about the medical situation other than to say that, yes, it played a part. This is certainly not unprecedented and happens from time to time.” Steve Whitmore, the sheriff’s spokesman, said. He explained that she would be confined to home for another 40 days and required to wear an electronic ankle tag.

“I have directed my criminal branch to immediately explore all possible legal options to ensure that the law is being applied equally and justly in this case,” said Rocky Delgadillo, the Los Angeles City Attorney.

Later, a “The city attorney filed a petition for an order to show cause why the sheriff should not be held in contempt for releasing Ms. Hilton, and demanded that she be held in custody,” Superior Court spokesman Allan Parachini said late Thursday afternoon.

In January Hilton pleaded guilty to charges of reckless driving and was sentenced to 36 months probation. She was then stopped while driving on a suspended licence twice more — on January 15 and February 27 — before being charged with violating probation. She had checked into the jail on Sunday night, after a surprise appearance at the MTV Movie Awards. “I am trying to be strong right now,” she said. “I’m ready to face my sentence. Even though this is a really hard time.”

In her short stay Hilton was housed in the “special needs” unit, which is separated from other inmates and is reserved for police officers, public officials, celebrities and other high-profile inmates. She did not have a cellmate.

Richard Hutton, her lawyer, said this week that his client had been doing well in jail. “She’s using this time to reflect on her life, to see what she can do to make the world better and hopefully, in my opinion, to change the attitudes that exist about her among many people,” he said.

There were reports last night that Hilton had been suffering from psychological trauma and refusing to eat prison food, and that doctors had been advising prison staff that she was on the verge of a breakdown.

Times recommends

• McDonald’s: the world’s local restaurant
• Help me to be a mum: a foyer to fulfilment
• A life online: God likes a laugh