Christian Poulsen's agent has confirmed that his charge did sign a pre-contract with Spanish side Villarreal - but it was cancelled last month.
Milan are keen on the Dane and already held talks before he signed a deal with the Spaniards.
However, the Italian giants have insisted on seeing evidence that the Schalke midfielder is not already tied to another club before re-opening talks.
Jorn Bonnesen - Poulsen's advisor - insists that their agreement with The Yellow Submarines was terminated.
"I am 110 percent certain that we are right." Bonnesen told BT.
"It would not have been particularly logical in any case if I had agreed a contract which only gave Villarreal the right to cancel it.
"The right to cancel the deal expired on March 10 and on March 9, we notified Villarreal that we wanted to use it."
Milan, who have are looking for a defensive midfielder and have also looked at Middlesbrough's George Boateng, will look to talk again with Poulsen this month.