The Scotland captain, who did not play between March and September with what United previously called a virus, has been diagnosed with ulcerative colitis, a chronic inflammatory bowel condition.

The 27-year-old was on the bench last Wednesday when the Premier League champions lost at Basel in the Champions League. He last played on Nov. 22 against Benfica, scoring in the 2-2 draw.

“Whilst he was able to maintain remission of symptoms for a considerable period this has proved more difficult recently,” United said Tuesday on its website. “Darren’s continued desire to play and his loyalty to both his club and country has probably compromised the chances of optimizing his own health and fitness.”

Ulcerative colitis is a chronic inflammation of the digestive tract. Symptoms can include diarrhea, abdominal pain, blood loss, weight loss and fatigue. There’s no known cure.

“He has … accepted medical advice to take an extended break from the demands of training and playing in order to afford the best chance possible of achieving full remission once again,” United said. “We request that his privacy is respected and hope that the removal of the additional stress associated with speculation regarding his health will also aid his recovery.”

Fletcher has played 10 times for United this season and made five appearances for Scotland.

“I am obviously absolutely devastated for Darren because I know how hard he has worked to get back to playing regularly for his club and country,” Scotland coach Craig Levein said. “He is one of the most inspirational players I have had the pleasure of working with and on behalf of his Scotland teammates and my backroom staff I sincerely hope this time off, allied to the support of his family, will enable him to make a full recovery.

“Darren has shown tremendous dedication and fortitude, demonstrated by his ability to overcome this illness and perform at the highest level for Manchester United and Scotland.”

Levein stressed that Fletcher needs time to “rest and recuperate.”

“He is a central part of our plans for the World Cup 2014 qualifiers but at this stage his health is paramount,” Levein said.

While Fletcher has never appeared at major tournament for Scotland, he has won four league titles, the Champions League, an FA Cup and two League Cups since making his debut for United in 2003.

Fletcher signed a four-year deal with United in March, securing his place at the club until 2015.