HS LOS ANGELES -  A number of celebrities have reached out to Michael Buble after his son was diagnosed with cancer.

Stars including Ellen DeGeneres, Sharon Osbourne and Ronan Keating have all taken to their Twitter account to show their support for the star after he revealed that his son Noah, three, with wife Luisana Lopilato, is being treated for cancer.

Sharon wrote: ‘’Sending positive thoughts and prayers to @MichaelBuble and Luisana for their son Noah,’’ and Ellen said: ‘’@MichaelBuble & family, we send you lots and lots of love.’’

Ronan added: ‘’My thoughts and prayers are with my friend @michaelbuble and his family at this time. Heartbreaking. #staystrong,’’ while Josh Groban tweeted: ‘’My family & I send all our love &prayers to @michaelbuble’s 3 year old son Noah as he fights cancer. Stay strong little guy’’.

The messages of support came after Michael announced the sad news on his Facebook page.

He said: ‘’We are devastated about the recent cancer diagnosis of our oldest son Noah who is currently undergoing treatment in the US. We have always been very vocal about the importance of family and the love we have for our children.

‘’Luisana and I have put our careers on hold in order to devote all our time and attention to helping Noah get well. At this difficult time, we ask only for your prayers and respect for our privacy. We have a long journey in front of us and hope that with the support of family, friends and fans around the world, we will win this battle, God willing.’’

But friends of the couple - who also have an eight-month-old son Elias together - say Noah is a fighter.

An insider told Us Weekly: ‘’They are really sad but hopeful. They immediately got him very good care and they are hoping and praying for the best.

‘’They are getting him the best doctors around. It’s really heartbreaking. This was a real shock, but they are doing everything they can.

‘’They’re staying positive and Noah is a fighter.’’