Milligan had impressed in his first season in Scotland, managing 31 apperances for Hibs.

Heckingbottom, who was appointed as Neil Lennon's replacement in February, admitted it was difficult to let the midfielder go.

"It was a killer for me," he told The Edinburgh News. "That's one of the two things I've done when I've been managing that hurt. It's tough sometimes.

"You make decisions and people say it's part of the game and it is, but he's a real good bloke and he's done great for me.

"Sometimes it's easy if you sit someone down and tell them why they can't be in your team as a footballer or as a person. He's done great but you have to trust your gut and that's what I've done with.

"But it was tough that one. It was tricky."

Milligan had a year left to run on his deal after joining the Scottish side from Melbourne Victory in 2018.

Heckingbottom explained that he decided to get rid of the 33-year to "change everything about" and used a loophole in his contract to do it.

"It's just to change everything about," he said. "We've got that opportunity. There's a break in Mark's contract and we just took advantage of that really.

"It's harsh on him but in all honest if I want to recruit something different to play in that position, then that'd be harsh too - keeping him in the building and not playing him."