"The first day back training he wasn't fit and hasn't been fit to train since," Redknapp told Get West London.
"Then he said he was going to Milan last week. He hasn't gone so what we need to do with him is get him fit. He's got to train morning, noon and night really, whether he stays here or goes somewhere else.
"I've got a lot of time for Adel. He needs to get himself in shape, like the other lads have done. If he does that he will be a great asset to us I’m sure.
"He's got fantastic ability and a point to prove really in the Premier League.
"He went to Fulham last year and it didn't go for him. He went to Milan and did great. If he was here he would be a big asset to us. We need him fit and ready to play."
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