Bobbi Kristina Brown
It has been alleged that the 21-year-old was under the influence of drugs when she was found unconcious in the bath. Fred Prouser/Reuters

It has been alleged that Bobbi Kristina Brown was under the influence of drugs on the morning she was found face down and unresponsive in the bathtub at her Georgia home.

According to the Daily Mail, People magazine reported multiple sources as saying that the 21-year-old had been using cocaine, heroin and Xanax and had been drinking heavily before the incident on January 31.

The daughter of the late Whitney Houston and Bobby Brown was reportedly "in and out" of rehab for three years after her mother's sudden death in tragically similar circumstances.

The 49-year-old singer was found face down and unconscious in the bath tub of a Beverley Hills hotel. Three years on and Bobbi Kristina was still struggling to come to terms with her mother's death.

Bobbi Kristina was previously hospitalised after allegedly mixing alcohol with sedatives and was photographed being taken to hospital on a stretcher.

Whitney Houston's personal driver has claimed that he witnessed the singer and her husband Bobby Brown smoking crack in front of their five-year-old daughter.

Al Bowman, who worked for Houston for two decades, told the Daily Mail that he observed at close quarters, the singer's descent into drug addiction and how she openly smoked crack in front of Bobbi Kristina.

He recounts an incident in his car in 1998, when the I Will Always Love You singer placed a thin pipe filled with crack cocaine to her lips, as her five-year-old daughter looked on.

The reality TV star has been in a medically induced coma and placed on life support following the incident almost a month ago. Earlier this week she was taken off her ventilator and given a tracheotomy.

Her father Bobby Brown has asked the media not to interview members of the extended family and respect the family's privacy as his daughter fights for her life.

Family members had earlier reported that the singer wants to keep his daughter on life support and is refusing to give up on her as the family hope for a miracle.

Meanwhile, police in Roswell, are investigating the circumstances leading to Brown's discovery in the tub and have opened a criminal investigation into the matter after Bobbi Kristina was found with bruises on her body. TMZ reported that it was told by multiple sources that police are looking into a "possible altercation" more than an hour before Ms Brown was found.