AC Milan are in danger of being banned from European competition for breaching financial fair play rules after their case was referred to the adjudicatory chamber of UEFA's club financial control body.
The 18-time Serie A champions have been under the regulatory body's microscope ever since Chinese investors Rossoneri Sport bought them for more than £600 million in April 2017, with the scrutiny increasing when they spent more than £200m on players last summer.
The club had hoped to make a voluntary agreement with UEFA to restructure their finances but that was rejected in December, and the investigatory chamber of the club financial control body (CFCB) has now decided to escalate the matter.
FFP was introduced in 2011 to tackle European football's chronic debts and over-spending. Its central principle is that clubs must "break even,'' or spend only what they bring in, although some additional investment from owners or investors is allowed.
The concerns around AC Milan are related to their owners' ability to repay loans they took out to finance the purchase of the club.
American hedge fund Elliott Management is reported to have loaned Rossoneri Sport, which is fronted by AC Milan president Li Yonghong, more than £250m and these loans must be repaid by October, together with more than £40m of interest.
UEFA said: "After careful examination of all the documentation and explanations provided by the club, the CFCB investigatory chamber considers that the circumstances of the case do not allow the conclusion of a settlement agreement.
"In particular, the investigatory chamber is of the opinion that, among other factors, there remains uncertainties in relation to the refinancing of the loan and the notes to be paid back in October 2018.''
It added that the adjudicatory chamber will make its decision "in due course'' and the investigatory chamber will announce if it is pursuing cases against any other clubs next month.
AC Milan finished the Serie A season in sixth place, good enough for a place in next season's Europa League, but it was another disappointing campaign by their standards. They lost 5-1 on aggregate to Arsenal in the last 16 of the Europa League and were beaten 4-0 by Juventus in the final of the Coppa Italia.
The CFCB has a range of sanctions it could levy, going from the withholding of prize money to fines to bans from European club football.
The most high-profile FFP cases in the past have involved Manchester City and Paris St Germain, who were both fined €20m in 2014, but recent seasons have seen a reduction in the number of sanctions as clubs have learned to live within their means.