Derby County say they adhered to the EFL's profit and sustainability rules when selling Pride Park stadium to club owner Mel Morris and have offered to show Championship rivals Middlesbrough the records to prove it.
The Riverside club have threatened to sue the Football League in regards to Derby's stadium sale believing that the Rams have broken the rules to gain an unfair financial advantage over their rivals.
But in a statement on the club's website Derby claim that Pride Park was subject to an independent valuation prior to the sale, which was then approved by the EFL.
"The stadium was subject to an independent professional valuation before sale, nearly 18 months ago, and the EFL indicated in writing that the arrangement was in accordance with its rules and regulations," read the statement.
"The EFL cannot now, long after approving the arrangements, suggest Derby County breached the rules," read a statement on the club's official website.
"The Club regrets that Middlesbrough Football Club have said they are suing the EFL over the matter, but that is a matter for them.
"Derby County offered to show Middlesbrough its financial records but they declined the invitation and appear to have decided to bring a claim against the EFL instead.
"The outcome of that action could not now affect Derby County, which has already had its financial returns for the relevant season approved by the EFL, and the Club is solely focussed on the current season.
"The Club will not be making any further comment at this time."
Derby sold Pride Park to Morris for £80m and in April boasted a profit of £14.6m - the first season in ten years that the club had made a profit.
