The 27-year-old joined Milan in the summer after spending 2010-11 on loan at Juventus, having been deemed surplus to requirements at the Premier League club.
He has been a regular at San Siro, with 22 competitive appearances to date, and his representative is confident that Milan are interested in signing the player.
"As it was agreed, a permanent deal will automatically be struck once he makes 25 appearances," Franco Zavaglia told milannews.it.
"I do not think that Milan will pass up on Aquilani. There is no problem about this, a permanent deal is something we all expect."
The Rossoneri, who are four points clear at the top of the Serie A standings, will visit Parma on Saturday in their upcoming league fixture.
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