The 21-year-old joined from Seville for pounds 17m at the start of 2004, but has recently been linked with a move from Highbury, and his agent, Jaime Rodriguez, said: "It is an honour for Reyes that Real are interested in him, but they know the path they have to follow. If the clubs can reach an agreement there will be no problem."
Some reports have suggested that any deal taking Reyes to Real Madrid would see the England striker Michael Owen move in the opposite direction.
"It was a long time, around eight years ago, when they first showed an interest and now the rumours are starting up again," Rodriguez added.
Reyes began the season well but his recent drop in form has led to speculation that he is struggling to settle in London
One player definitely planning to leave the country is Dwight Yorke, who has been approached by the Australian club Sydney FC and is said to be keen about the move.
Yorke, out of favour at Birmingham, has been targeted by Sydney as their "marque signing" for the inaugural Hyundai A-League season in 2005-06 .
Sydney confirmed they have approached Yorke's representatives, SFX, and said they have received permission to discuss a deal with the Birmingham manager, Steve Bruce. Sydney have already signed the former Aberdeen striker David Zdrilic and the former Leicester and Wolves midfielder Steve Corica.