Askou, 26, played against a Manchester United XI at the weekend, the third time he has featured in pre-season, and looked a calm and assured presence at the back first alongside Gary Doherty and later alongside Michael Nelson.
The defender, who has just finished a spell in Turkey, has returned to denmark for the moment but is considering an offer.
Bryan Gunn has used the trial system well this summer, bagging Paul McVeigh after he impressed, and offering Goran Maric a deal, the outcome of which has yet to be revealed. Another striker, Kris Bright, showed promise and is worth a second look at Selhurst Park tomorrow night against Crystal Palace.