The Dutch international has made 51 league appearances - netting 11 times - since joining the Madridistas in 2007.
However, following the expensive acquisitions of Kaka, Cristiano Ronaldo, Karim Benzema, Alvaro Arbeloa and Xabi Alonso, reports have suggested that Real are open to offers for Dutch quintet Sneijder, Rafael van der Vaart, Arjen Robben, Roysten Drenthe and Ruud van Nistelrooy, while Klaas-Jan Huntelaar is set to join AC Milan.
Sneijder himself - who has been capped 52 times by his country - has been linked with moves to Chelsea, Arsenal, Tottenham Hotspur, Aston Villa and Inter Milan.
And Villa Park chief O'Neill has admitted that a player of Sneijder's calibre would interest him if he was available.
"I think that the more creativity you have in your side the better chance you will have," he said.
"If there were players like Sneijder, who have great talent and might be surplus to requirements at a club that is buying, then I think you should be interested, even if that interest is not reciprocated.
"Because how else are you going to try and improve your team?"
NEWS: Sneijder switch to San Siro ruled out
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