Former heavyweight boxing champion Mike Tyson's four-year-old daughter is in critical condition after she was found with a cord around her neck following an accident, according to media reports on Monday.

Exodus Tyson was playing near some exercise equipment when she accidentally got tangled in a cord or rope hanging from a treadmill, the Arizona Republic reported on its website.

The Phoenix Police Department did not immediately return phone calls.

ABC News reported that the child was rushed to St. Joseph's Hospital and Medical Centre in central Phoenix, where she was listed in critical condition on life support.

Police said that based on the initial investigation, the incident appeared to be "a tragic accident," ABC reported.

Tyson is the subject of a new documentary by director James Toback. He was not in Phoenix at the time of the accident, but was shown later on television news arriving at the hospital.