Tyson rushed to his daughter's bedside from Las Vegas [GALLO/GETTY]

The girl, identified by media as Exodus Tyson, was found by her seven-year-old brother on Monday morning at her house in Phoenix, Arizona in the United States.

Her mother, summoned from another room, freed her, called emergency services and tried to resuscitate her.

'Tragic accident'

"Initial information developed today from officers, initial interviews and a preliminary examination of the scene indicate this was a tragic accident," said police spokesman Andy Hill, who added the girl was in "extremely critical condition".

"Somehow she was playing on this treadmill, and there's a cord that hangs under the console – it's kind of a loop," Hill said.

"Either she slipped or put her head in the loop, but it acted like a noose, and she was obviously unable to get herself off of it."

Tyson, who doesn't live at the house, had been in Las Vegas but travelled to Phoenix upon learning of the accident, Hill said.

Local television station KNXV-TV reported he arrived at St Joseph's Hospital in a taxi and made no comment as he hurried to the child's bedside.

New York city public relations firm 42West issued a statement on the family's behalf.

"The Tyson family would like to extend our deepest and most heartfelt thanks for all your prayers and support, and we ask that we be allowed our privacy at this difficult time," the statement said.

Tyson had been in the news this month with the US release of the film Tyson, a documentary directed by James Toback that premiered at the Cannes Film Festival last year.

It offers an engrossing portrayal of the turbulent life of Tyson, from his humble beginnings on the mean streets of Brooklyn to his phenomenal rise as the youngest heavyweight world champion in history, through his epic fall marked by addiction, humiliation in the ring and a rape conviction.