Uefa said on Monday it had ordered accusations that Paris Saint-Germain has broken its financial fair play rules to be referred to its financial unit "for further investigation".
European football's governing body initially opened an investigation into the Qatari-owned club's spending in September 2017 under pressure from some of Europe's biggest clubs after the French club signed Brazilian midfielder Neymar for a world-record €222 million (then Dh965.6m).
Within weeks the club had also agreed a deal to sign teenage striker Kylian Mbappe from Monaco for €180m.
In June, Uefa's Club Financial Control Body (CFCB) closed its investigation only to re-open it just a month later.
📅 This week's schedule
— Paris Saint-Germain (@PSG_English) September 24, 2018
Monday🏋️♂️
Tuesday🎙🏋️♂️
Wednesday ⚽⚡ #PSGSDR ⌚21h00 CET
Thursday🏋️♂️
Friday 🎙🏋️♂️
Saturday ⚽⚡ #OGCNPSG ⌚ 17h15 CET
Sunday 😴
🔴🔵 #AllezParis pic.twitter.com/Hj3whMOc7H
Uefa said on Monday the case had now been referred "back to the CFCB Investigatory Chamber for further investigation".
Meanwhile, France World Cup star Kylian Mbappe will sit out one further league game for PSG after losing an appeal against a three-match suspension on Monday.
Mbappe, 19, was handed the sanction for lashing out in retaliation at Teji Savanier during a feisty 4-2 win at Nimes on September 1.
Savanier was handed a four-match ban for his role in the incident, a sanction that was also confirmed following appeals by both players, the French Football Federation (FFF) announced.
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Mbappe, who is being tipped to win the prestigious Ballon d'Or award in December, notably on account of his performances for Les Bleus in Russia last summer, has served two of his three matches so far.
He sat out a 4-0 home win over Saint Etienne and again on Sunday as PSG beat Rennes 3-1 away to reinforce their lead at the top of the table.
Mbappe will sit out PSG's next league outing, at home to Reims on Wednesday, and will be eligible to return for PSG's trip to Nice on Saturday.
He did play and score in PSG's Uefa Champions League defeat at Liverpool last Tuesday as the suspension does not cover European games.
PSG hold a five-point lead over second-placed Lille after six league games of the season.