Delph saw a specialist on Tuesday to confirm his worst fears that he is facing another lengthy spell on the sidelines. He suffered the latest in a long line of injury blows during last Tuesday's npower Championship clash with Coventry.
McLeish said: "Delph is not fit. I don't know if he will play again this season but he's rolled his ankle sufficiently enough to rule him out (for some time)."
He added: "It's a shame because we wanted him to go out and play regular games to see if he could get over those ailments that he's had.
"Hopefully, if he comes back stronger in the summer then we will see a different Delphy."
Delph, who was signed from Leeds for £6million by previous Villa manager Martin O'Neill, had a long spell out of action after rupturing his cruciate ligament in April 2010.
He then suffered an ankle setback towards the end of last season which required surgery and this season a series of minor setbacks have curtailed his progress.
Delph played five games on loan to Leeds and his spell at Elland Road was due to end this weekend.
Source: PA
Source: PA