Jack Osbourne claims he was fired by email after being diagnosed with multiple sclerosis.

The 'Adrenalin Junkie' host was ''offended'' when an undisclosed TV company decided he wouldn't be up to the tasks in a reality contest without speaking to him first.

Jack - who was diagnosed with the debilitating condition five weeks ago - said on 'The Talk': ''I had booked a job, right when I got diagnosed and the company didn't think I could actually perform the job.

''Out of everything, that's what has really ticked me off the most because it's like, 'Don't tell me what I can and cannot do.' At no point did they call me.

''It was all through agents and lawyers - I was offended by it.''

It is believed the show was 'Stars Earn Stripes', which sees soldiers put celebrities through military exercises.

A programme source admitted to The Sun newspaper that it was felt Jack wouldn't be up to the challenges, but said it was ''hard to believe'' he was informed by email.

Jack's mother Sharon Osbourne later hit out on twitter, saying the 26-year-old star was fired because the company felt he was a ''liability''.

She wrote: ''Yes @MrJacko was fired. They said he was a liability & were so personable, sent an email to let us know.''