An autism activist says that John Travolta’s chronically ill son Jett’s death, who is believed to have died after hitting his head on a bathtub following a seizure, could have been avoided had his Scientology practising parents decided not to follow their religion’s anti-medicine theories.

Sixteen-year-old Jett was speculated to have been suffering from autism, a brain development disorder that impairs social interaction and communication, and also produces restricted and repetitive behaviour.

The activist said that the health problems of the teenager, who began suffering from seizures at the age of two, could have been better treated with medicines.

"Anti-seizure medication could have controlled the attacks," the New York Post quoted the activist, who requested not to be named owing to her friendship with Travolta’s brother, Joey, as saying.

"I believe this is something that was totally avoidable.

"There were such clear indications that this kid had autism. It’s bothered me for years.

"The irony is not lost that Joey has committed his life to working with autism and disabilities, and his brother, for religious reasons, would let this happen," the activist added.

The ’Pulp Fiction’ star and wife Jelly Preston have repeatedly denied the claim, saying that their son suffered from Kawasaki syndrome - a rare illness that leads to inflammation of the blood vessels in young kids, with the most serious effect on the heart.

They also insisted that a detoxification program based on the teachings of the Church of Scientology had helped their son during earlier medical problems.