John Travolta holding private memorial today

John Travolta is holding a private memorial for his teenage son today (08.01.09).

The 54-year-old actor and his wife Kelly Preston have planned a Scientology service for 16-year-old Jett - who died last week following a seizure at their Bahamas hotel - at their Florida estate.

The couple are believed to have invited fellow followers of the controversial religion Tom Cruise, Oprah Winfrey and Kirstie Alley to the service.

A family friend said: "Forget that John is a big Hollywood star. He is just a grieving father who is struggling to cope with the loss of his beloved son."

Senior Scientologists from the religion's Florida centre are expected to lead the memorial.

John is struggling to cope with Jett's death, and is planning to take time out from his hectic work schedule to help him get over the tragedy.

The source explained: "He isn't ready to face the public, and won't be for some time.

His grief is raw and it is going to take him and Kelly a long time to recover from this."

Jett suffered from Kawasaki disease - a rare condition which causes the inflammation of the vital organs and blood vessels - and suffered from fits since he was a toddler.

He had been on medication to control the seizures, but John and Kelly reportedly took him off it amid fears it was harming his health.

A Scientology service consists of eulogies and music like other mainstream religions.

Practitioners of the religion do not believe in heaven or hell, but claim individuals will live again in another body.

A spokesman for the religion explained: "At a service, friends and family have the opportunity to say goodbye, to acknowledge and thank the person for what he or she has done in this lifetime, and to wish them well as they move on to their next lifetime."