The 22-year-old won the Belgian Golden Shoe in 2008, an award given to the player considered to be the most valuable in the Jupiler League.
However, Defour missed the majority of last season with a broken leg - an injury which prompted Red Devils chief Sir Alex Ferguson to send Defour a letter wishing the Standard Liege star a speedy recovery.
“Sir Alex is always interested in Steven ever since he sent him the letter when he was struggling with injury. He is interested but we have to wait for an offer to be validated," Paul Stefani told Sport.co.uk.
"At the moment he is not 100 percent because of his long term injury, and now he has to work on recovering from this."
The Old Trafford outfit are not alone in their interest in Defour with Chelsea, Liverpool and Manchester City also rumoured to be keen on the playmaker.
Stefani stated that any move hinges on when his client regains full fitness
"Yes, they are interested, but many clubs are interested, from Spain, Italy, and Germany. To say that tomorrow he will go to England is not right.
“There is always interest and everyone wants to play in the Premier League because it is a very big competition. But, I think we will have to wait until he is a 100 percent fit, not 85 percent."
United's need for new midfielders will soon become greater, with Paul Scholes and Ryan Giggs in the twilight years of their careers, while both Owen Hargreaves and Anderson are nursing injuries on the sidelines,
By Ian Woodcock
