The 24-year-old England forward's contract expires in the summer of 2012 and it is understood talks over a new deal have broken down.
"I can't really give an answer about this," said Ancelotti.
"He has some problem at this moment but when a big team has top players like Rooney, they want to keep him."
Ahead of Chelsea's Champions League match against Spartak Moscow in Russia on Tuesday, Ancelotti was asked several times if Chelsea would bid for Rooney in the January transfer window but the Italian refused to be drawn on the matter.
"If you want to know what players Chelsea want to buy and how much money they want to spend on players you should ask Roman directly," he added, referring to the club's billionaire owner, Roman Abramovich.
United chief executive David Gill has promised to give the media a "statement at the appropriate time".
United boss Sir Alex Ferguson is widely expected to discuss Rooney's future at a news conference on Tuesday ahead of the Champions League game with Bursaspor on Wednesday.
Manchester City and Real Madrid have also been linked with Rooney, though the Spanish club's coach Jose Mourinho predicted the striker would stay at Old Trafford.
"I don't think he will leave," said Mourinho, ahead of Real's Champions League match with AC Milan. "I think Ferguson will persuade him to stay."
Earlier on Monday Real director general Jorge Valdano also appeared to quash speculation of an imminent move for Rooney, who has not scored for United from open play since March -although he did not rule one out in the summer.
He told Telemadrid: "The question is, who would we move aside if we signed another striker? In January, there will be neither ins nor outs. June is a long way away."
Like Mourinho, Arsenal boss Arsene Wenger also predicted Rooney would stay at Old Trafford.
"I am convinced he will stay at Manchester United because it is his club. They have the power to keep him and I don't believe in the story," he said.
Real's arch-rivals Barcelona are also rumoured to be interested in Rooney, whose value is likely to drop as his contract nears expiration.
The England striker's relationship with Ferguson has been under scrutiny in recent weeks.
The striker missed United's Premier League fixture at Everton last month after allegations about his private life and he was then left out of subsequent games by Ferguson, who claimed the England international had an ankle injury.
However, last Tuesday, after England's 0-0 draw against Montenegro in a Euro 2010 qualifier at Wembley, Rooney contradicted the Scot's statement and insisted he was fit and had not had any ankle problem.
On Saturday Rooney, who has scored only one goal in five Premier League appearances for United this season, was left out of the starting line-up for the 2-2 draw with West Brom.
Ferguson brought his striker on with 20 minutes remaining, after United had squandered a two-goal lead, and asked him to play on the left wing.
From BBC
Source: http://www.manutd-blog.com