Uefa promise hard line on City's £400m windfall deal

European governing body investigates if sponsorship deal breaks Financial Fair Play rules

Manchester City's ground-breaking £400 million sponsorship deal will face a Uefa investigation amid growing concerns it could breach the new Financial Fair Play rules. European football's governing body have promised City's envious rivals that they will take expert advice on whether the Etihad Airways agreement, announced amid considerable fanfare on Friday, is against its new code, monitoring of which began last month.

Last night supporters groups rounded on City, claiming the deal drove a "coach and horses through the market place". Uefa will be under intense pressure to ascertain whether the £400m is artificially inflated to help City comply with the new rules.

Etihad is the national airline of Abu Dhabi, whose ruler is the half-brotherof City's owner Sheikh Mansour.

"Uefa will use relevant experts to make assessments as to the fair value of any major sponsorship deals, using appropriate industry benchmarks," a spokesman told The Independent on Sunday. "These will then be considered by the Club Financial Control Panel, together with any relevant information the clubs present regarding the deals, when they assess the break-even requirements."

City, who are expected to announce losses in two months' time in excess of last year's £121m, insist the deal is based on legitimate market values and will help them move towards meeting the FFP requirements of losing no more than ¤45m (£40m) in the three years to 2014-15. Clubs must effectivelybreak even by 2018 or face being barred from European competition.

Bayern Munich's chief executive, Karl-Heinz Rummenigge, who is also the chairman of the European Club Association, has said: "Perhaps they know a trick which I don't that will allow them to take part in the Champions' League."

Last night a spokesman for the Arsenal Supporters' Trust said: "It's like a match where one side decides to follow the offside rule and one doesn't. The City deal drives a coach and horses through the market place."