BRITNEY Spears has been likened to Anna Nicole Smith in a tell-all interview that claims she abused cocaine and prescription drugs and nearly had a fatal overdose of ecstasy.

It comes as it emerged Spears was treated by paramedics on Sunday after a call by worried rehab centre staff.

Ambulance crews turned up at Malibu's Promises clinic where Spears is fighting alcohol abuse. They were closely followed by Spears's mother Lynne, ex-husband Kevin Federline and their two children Sean Preston and Jayden James.

Officials have confirmed Spears was in difficulty "but didn't say why", a witness said.

Meanwhile, Spears's childhood pal Jason Alexander, whom she wed in Las Vegas in 2004, claims he had to break his silence on Spears because he fears she'll end up dead like tragic model Smith.

Alexander, who claims they once had a drug-fuelled threesome with a female dancer, told London's Sunday Mirror: "It freaked me out when I saw she had shaved off her hair; that was clearly a cry for help."

Alexander said he couldn't keep up with her drug use when they were lovers. He claims Spears almost had a fatal overdose on MDMA, or pure ecstasy, in a Las Vegas hotel suite in the days before their whirlwind 55-hour marriage. He said she was unconscious and having trouble breathing.

"I remember looking down at her all crumpled in the bathtub. She looked so white and lifeless. I thought she was dead. I thought, 'This bitch is going to f...ing die right in front of me'."

He added: "We used ecstasy at night to party and cocaine during the day to stay awake. Then we would take downers like Valium or Vicodin to come down and rest. She definitely had a problem with drugs when we were together."

LINK