Strong has had a succesful loan spell with United, but the club may only be able to pay his wages if promotion is clinched through the playoffs.
Strong joined the Tigers in the close season, but picked up an injury early into his Boothferry Park career and wasn't able to impress new manager Peter Taylor.
Defender Andy Holt was also told that he would be leaving the club in the summer, with chairman Adam Pearson saying that he wants to run a squad of 20 senior professionals.