The 20-year-old has spent the entire campaign on loan with Championship side Wigan Athletic and some speculation has suggested that he has been deemed surplus to requirements at Old Trafford.
Although he did not confirm that Powell is a target of his, Celtic boss Neil Lennon has admitted that he did attend last weekend's FA Cup semi-final between Arsenal and Wigan Athletic, where Powell came off the bench.
"We are looking now to build for the Champions League qualifiers," Lennon told the Daily Mail. "I was at Arsenal vs. Wigan last weekend, looking at a couple of players down there and some of the staff are away looking at potential targets.
"The phone is beginning to hot up with agents and potential players, and we're just going through those lists. We have the capacity to spend if the player fits the criteria of having resale value."
Powell joined United from Crewe Alexandra in 2012.