Manchester United slapped a 'not for sale' sign on striker Cristiano Ronaldo Friday following the Portuguese international striker's most recent bid to pave the way towards joining Real Madrid.

Ronaldo has been linked with the nine-times European champions since he hinted at a move to Real five days before United's triumph over Chelsea in the Champions League final on May 21.

And after Portugal were ousted from the Euro 2008 Thursday following a 3-2 defeat to Germany, the 23-year-old said he would announce his future intentions in "two to three days".

However United have moved quick to quell speculation of a big-money move for their coveted star, and appear to have dug their heels in over the issue in a statement on their website.

"Further to Friday's press speculation about where Cristiano Ronaldo's future lies, the club has moved to reiterate its stance on the matter: United are not listening to offers," said the statement.

"Ronaldo has continually been linked with a move to Spanish side Real Madrid this summer.

"However, the club reaffirmed its position to ManUtd.com on Friday morning. And the message is simple: the 23-year-old United star is 'not for sale'."

Ronaldo told reports after Thursday's defeat: "There will be news in the coming days.

Asked about a move to Real, he said: "It's a big possibility, but it doesn't just depend on me.

"I think a concrete offer has been made (from Real), but we'll see what happens in the next few days and whether we can come to some kind of agreement."

Real are reportedly willing to pay United 80 million euros for the Portuguese striker, however Ronaldo - whose contract with United does not expire until 2012 - admitted that "negotiations (to leave the club) would be difficult".

He said he hoped to talk to United bosses, and seemed to leave no doubts over his preferred destination, adding: "Everyone knows what I want, and what my dream is.

"I hope to have talks with United. Hopefully everything will be decided in two to three days time."

Ronaldo also said he will undergo a foot operation in Manchester in the coming days to remedy a problem that he said had plagued him in recent weeks.