The controversy comes because of City's £400m sponsorship deal with Etihad, which is the national carrier of Abu Dhabi. City's chairman Sheikh Mansour bin Zayed bin Sultan Al Nahyan is the half-brother of Abu Dhabi's ruler and of Etihad chairman Sheikh Hamed bin Zayed al-Nahyan.
The Independent says that UEFA's Licensing and Fair Play regulations take the view that a club and sponsor are related parties if a family relationship exists and if money comes from a "close member" of the club owner's family who "has significant influence over the [club]".
Sheikh MansourThe paper speculates that City will have to demonstrate that other members of Sheikh Mansour's family do not exert that kind of influence over him. City say they have discussed the deal with UEFA and argue that the details of it, which the club has not disclosed, represent fair value in a groundbreaking structure.
He went on: "If UEFA do actually show some teeth and investigate it then Man City will be obliged to show that the transaction was an entirely commercial "arms length" transaction.
Wenger and HenryBut Wenger said the deal threatened the credibility of UEFA, which is seeking to enforce new Financial Fair Play rules which prevent clubs spending more than they earn. "Sponsorship has to be at the market price" he said accusing City of sending the message that "they can get around it by doing what they want".
And Liverpool owner Henry said: "Mr Wenger says boldly what everyone thinks". On hearing of the deal, he'd asked: "How much was the losing bid"", inferring that City had not looked for other sponsors because they were arranging an inflated bid with Etihad.
City have called Wenger's remarks "unfounded and regrettable", while UEFA have announced a team of "experts" will "make assessments of fair value of any sponsorship deal". But it's hard to see how anyone can challenge the fact that the market price is what the market is prepared to pay.
Some observers outside City's ranks see criticism of the deal as little more than sour grapes aimed at preventing a new side from breaking into what has become a cosy cartel of four top clubs, Manchester United, Chelsea, Arsenal and Liverpool.
They point to the fact that Liverpool have been out of the top four places for two seasons, and that Arsenal appear to be slipping backwards. There's probably an element of truth in that, but the real pressure here is on UEFA to show that Financial Fair Play can be anything more than a nice idea.