Sharon Osbourne says her son Jack Osbourne is doing ''really, really well'' in his battle against multiple sclerosis.

The TV presenter insists the 26-year-old star - who learned of his illness in April, just two weeks after his fiancee Lisa Stelly gave birth to their first child, Pearl Clementine - will survive the disease because of his ''positive state of mind'', and she has thanked everyone who has supported her son through the traumatic time.

Sharon - who overcame colon cancer - said: ''Osbournes survive everything. We really do. Jack is doing really, really well. He has such a positive state of mind.

''He is really a positive guy, a good guy. His whole life is that he gives back. It makes him feel good and that is just the way he runs his life.

''He does an awful lot for the programme he is under - Alcoholics Anonymous - and he wants to do as much as he can for MS.

''I have to thank you, everyone, for all their good wishes. It's been amazing for Jack because I really believe that vibes of prayer definitely help.''

Sharon - who is also mother to Kelly, 27, and Aimee, 28 - admits she doesn't spend enough time with her children and grandchild, so she often ''kidnaps'' them and takes them on impromptu flights to New York.

She explained in an interview to The Sun newspaper: ''I don't have enough time unfortunately as grandma, so I have to 'kidnap' my family and take them with me all the time.

''I am like, 'We are going out tonight.' And what I mean by tonight is that I put them on a plane and take them to New York.''

The 59-year-old star - wife of Ozzy Osbourne - has been a judge on 'America's Got Talent' since 2007, but she is yet to have been asked back on the talent show, despite auditions starting soon.

She added: ''Nothing is guaranteed in this industry. I don't know if they are going to pick me up tomorrow for 'America's Got Talent'.

''You go with the flow. We have all been let go or not had our contracts picked up.

''We are all big people. You dust yourself off and you go out the door.''