Former Oasis guitarist Paul Arthurs has pulled out of forthcoming gigs after being diagnosed with tonsil cancer.
The musician, also known as Bonehead, told fans he was going to be "taking a break for a while" in a statement posted on Twitter.
As a result, he will not appear with Liam Gallagher at gigs which had been scheduled for this summer.
Arthurs co-founded Oasis and played on several of the band's biggest albums, including debut Definitely Maybe.
He played rhythm guitar and keyboards for the band, also appearing on What's The Story (Morning Glory) and Be Here Now.
Arthurs left Oasis in 1999, but in recent years had begun to work with Gallagher on other projects.
He played with Gallagher's band Beady Eye in the mid 2010s, standing in for guitarist Gem Archer after he sustained a head injury.
Arthurs has also played on Liam Gallagher's solo albums and performed with him on recent tours.
Arthurs told his followers he would be starting a course of treatment soon. Tonsil cancer treatments can include surgery, radiation therapy and chemotherapy.
"Just to let you all know I'm going to be taking a break for a while," he said in a statement posted on his social media account.
"I've been diagnosed with tonsil cancer, but the good news is it's treatable and I'll be starting a course of treatment soon. I'll keep you posted on how it's going.
"I'm gutted I'm missing the gigs with Liam and the band. Have the best summer and enjoy the gigs if you're going, I'll see you soon xxx"
Gallagher sent his best wishes to Arthurs, tweeting: "Sending BIG love to the 1 n only Bonehead and his family wishing you a speedy recovery we're all thinking of you."
Former Oasis star Andy Bell also posted: "Get well soon Bone."