McLeish concedes Blues will either take up the option to sign Benitez permanently at the end of the current campaign or allow him to return to Mexican side Santos Laguna.
Former Scotland boss McLeish is still undecided about which route to pursue with the Ecuador international but concedes it may depend on the asking price.
McLeish said: "There's no mileage in getting 'Chucho' (Benitez) on loan for another season. The agreement was that we buy Benitez in May and that's the way it's written down and we'll make that decision as and when."
He added: "I did say a few weeks ago we'll try and keep him. But maybe it comes down to finance. It depends."
Benitez has scored only three times for City and has recently lost his place up front to James McFadden.
But McLeish insists Benitez has still made a telling contribution to City's first campaign back in the Barclays Premier League.
He said: "Chuch has done well for us. Maybe his lack of goals return is what people are questioning about him but he has made a big impact."
Source: PA
Source: PA