Amy Winehouse's friends fear she is "getting back to her worst"

Amy Winehouse's friends are begging the troubled singer to return to rehab -- fearing she is "getting back to her worst".

The 24-year-old singer -- who left a private London rehab clinic earlier this month, has slowly been returning to her old ways -- and her incarcerated husband, Blake Fielder-Civil has threatened to ban her from visiting him in prison because he is convinced she is still taking crack cocaine.

A source said: "Amy’s in an awful state again -- she’s clearly on drugs. Many of us think full-time residential rehab is the only option but she won’t go back."

The 'Rehab' singer's friends and family have been in crisis talks since Monday, after Amy, who has a history of self-harm, was seen with scratches on her left arm.

Amy checked into Central London's Nightingale Hospital after being exposed smoking a crack pipe in her London flat in January -- but pals believe that soul diva's rehabilitation was not taken seriously enough.

The source added to British newspaper The Sun: "She was smoking cannabis and drinking heavily as soon as she left rehab. That has now increased.

"Everyone who’s seen her in the last week or so has been really disturbed by the state she’s in. She’s getting back to her worst.

"It was hoped her new album and fashion range would keep her focused but it hasn’t worked."