The Belgium international is out of contract next summer.
The defender said earlier this month he is yet to discuss a new deal and hinted the Dutch club could let him go at the end of the season.
Frank de Boer: "We know that his contract expires in 2013.
"So it's either renew or relocate to a good foreign club, where Ajax would also benefit from a transfer fee.
"We already told Jan last year in Turkey that we are keen to hold on to him. We will open talks early in March to discuss a new deal."
