Last updated on .From the section Scottish

Former Celtic and Manchester United midfielder Liam Miller has cancer.

The Irishman, 36, is reportedly on his way back to Ireland from the United States, where he has been having chemotherapy treatment.

Miller, who won 21 caps for Republic of Ireland between 2004 and 2009, started his career at Celtic before moving to Old Trafford.

"I hope he can get through this difficult time of his life," said external-link former Celtic team-mate John Hartson.

"Obviously all our thoughts go out to him and his family," added Republic of Ireland manger Martin O'Neill.

"It puts everything in perspective" - Republic of Ireland manager Martin O'Neill

Former Celtic and Aston Villa captain Stiliyan Petrov, who recovered from acute leukaemia, said external-link : "I'm saddened to hear the news about my old team-mate Liam Miller. Be strong buddy and remember a few of us have beaten it. YOU WILL too my friend. I'm thinking about you."

Miller also played for Leeds United, Sunderland, QPR and Hibernian before heading to Australia.

Miller played for three clubs down under - Perth Glory, Brisbane Roar and Melbourne City - before returning to his native Cork City.

He also played for semi-professional American team Wilmington Hammerheads in North Carolina last year.

Miller celebrates a goal for Manchester United, but he struggled to establish himself at Old Trafford

News of Miller's condition has been met with messages of support.

Republic of Ireland international David Meyler said the squad are thinking about their compatriot ahead of their play-off match against Denmark.

"Obviously we heard the news," the Hull City midfielder said on Monday. "We're unsure about the details, but our thoughts go out to his family and we're just thinking about him and we just hope he can pull through and he's strong. That's from the whole team and everyone."

Celtic wrote on their official Twitter account: "The thoughts and prayers of everyone at Celtic Football Club are with Liam Miller and his family at this time."

And Manchester United tweeted: "The thoughts of everyone at Manchester United go out to Liam Miller and his loved ones at this difficult time."