Former Leeds United boss David O'Leary has questioned Tottenham striker Robbie Keane's loan move to Celtic.

O'Leary finds it hard to believe that £65,000-a-week Keane is happy to swap the Premier League for a much poorer stage.

O'Leary told the Scottish Sun: "We saw at Elland Road on Wednesday exactly why Robbie hot-footed it to Celtic. Jermain Defoe's hat-trick underlined just what he was up against at Spurs. Jermain has 20 goals already this season and Peter Crouch is always going to be the more obvious partner for him.

"It's not that Robbie's a bad player or Harry Redknapp no longer fancies him. It's just that he is competing against a player on fire. I know from working with Robbie at Leeds he does not take kindly to being left out of the team.

"He has a Wayne Rooney-like enthusiasm to play.

"No matter how much money he has, he just wants to play football - and so I can understand why he has gone to Celtic. But he will quickly realise that Scottish football is at a low ebb. He's gone from playing in Europe's top league to one which is ranked 15th.

"That's too big a drop for a player of his calibre. Sure, Celtic are a big club, one which almost everyone in Ireland wants to do well.

"But unfortunately the standard of the SPL has probably never been lower."