Celtic midfielder Arne Engels is reportedly undergoing a medical examination ahead of a transfer to West Ham United, according to Celtic manager Martin O'Neill. O'Neill confirmed the situation, expressing disappointment at the player's impending departure.

"Naturally disappointed, really, that he's leaving the football club, he's done very well for us," O'Neill stated. "And it's hard to dissuade him of that. If it hadn't come up, I think he'd have been happy. Even though the offer came in very late from Nottingham Forest in January, he never moaned about it at all."

O'Neill acknowledged that the move presents a significant opportunity for Engels that is difficult to turn down. He also noted concerns that a similar injury to teammate Alistair Johnston could jeopardize such a transfer.

"You've got a concern, I suppose, with the fact that Alistair played for us when there was an offer on the table, hurt himself, maybe things like that there may disappear," O'Neill said. "I suppose Arne was probably worried the same sort of thing might happen. From a playing viewpoint, I probably can understand that."

Johnston sustained a leg muscle injury during Celtic's 5-1 victory over Kilmarnock on Sunday and is expected to be sidelined for several weeks. O'Neill indicated that Johnston's injury is not long-term and he should recover fully.

Celtic has recently signed winger Haissem Hassan and midfielder Mika Baur. O'Neill anticipates further player acquisitions, mentioning Chelsea left-back Landon Emenalo as a potential loan signing to provide cover for Kieran Tierney. O'Neill expressed a desire to bring Emenalo to the club if his current injury clears up.

"I think he's a really fine young player," O'Neill said of Emenalo. "Obviously we need that position covered. Kieran did exceptionally well last season, having been plagued with injuries at Arsenal. He came roaring back, which was great. And this young man has definitely got talent."