REPUBLIC of Ireland manager Martin O'Neill has sent his support to former Sunderland player Liam Miller amid reports he is battling pancreatic cancer.

The 36-year-old midfielder is said to be undergoing treatment and news of his plight has been greeted with shock by acquaintances within football.

Speaking at his pre-match press conference ahead of Ireland's World Cup play-off second-leg clash with Denmark, the former Bhoys boss said: "I gave Liam his debut at Celtic. He played wonderfully well in a Champions League game one evening, he was absolutely outstanding.

"The news - we heard about it just recently, we didn't know how bad it was - and obviously all thoughts go out to him and his family. I think he's got three children as well.

"He's a very young man, 36 years of age. It puts things in perspective."

There was support too from fellow Corkman David Meyler, who said the 21-times-capped Ireland international is in the thoughts of the current squad.

Meyler said: "We've obviously heard the news. We're unsure of all the details, but our thoughts go to his family. We are thinking of him and we hope he can pull through and he's strong anyway.

"That's from the whole team and everyone."

Miller made his professional debut for Celtic in 2000 after coming through the youth ranks at Parkhead and helped them win the Scottish Premier League title in 2004.

The Scottish champions said in a post 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."

He then moved south to Manchester United on a free transfer, making 22 appearances under Sir Alex Ferguson in two seasons - which included a spell on loan at Leeds - before joining Sunderland in 2006.

United also used their official Twitter account to say: "The thoughts of everyone at Manchester United go out to Liam Miller and his loved ones at this difficult time."

Miller was part of the Black Cats' squad that won promotion to the Premier League in 2007 under Roy Keane, but he was on the move again in 2009, this time to QPR.

A short spell at Loftus Road was followed by stints at Hibernian, Australian clubs Perth Glory, Brisbane Roar and Melbourne City, home-town club Cork City and, most recently, Wilmington Hammerheads in America.

Cancer survivor John Hartson, who played alongside Miller at Celtic, tweeted: "My thoughts are with Liam Miller and his family this morning. Hope he can get through this difficult time of his life."

Jacob Burns, the former Leeds and Australia midfielder who is now head of football at Perth Glory, tweeted: "In shock! Thoughts and prayers are with my old team-mate and friend Liam Miller as he and his beautiful family fight through this battle!"