The Swedish international is believed to want a move away from the Nou Camp after Barcelona captured David Villa in the summer.
“We will meet Barcelona again on Thursday at midday,” Galliani told the club’s official website.
“The negotiations are very complex, very difficult, very expensive, but the relationship with Sandro Rosell is really good and he is very nice.
“The will of Barcelona is to sell the player to Milan, the availability of the player also like that.
“There is a lot of money to overcome and this is the difficulty.”