Southampton could be thrown out of the Championship play-off final following fresh allegations that the club spied on multiple opponents, not just Middlesbrough.
Evidence submitted to the English Football League reportedly supports claims that Tonda Eckert's side had an analyst observe at least one additional club's training sessions this season.
The EFL is expected to deliver its ruling next week, with a hearing scheduled for Tuesday at the latest.
Southampton have already admitted to watching a Middlesbrough training session before their semi-final clash, which they won in extra time on Monday to secure their place at Wembley.
Southampton's 'spygate' scandal has gripped the Championship
|GETTY
Several other Championship clubs have privately raised concerns about Southampton's detailed knowledge of their tactical approaches and set-piece routines during matches this campaign.
Middlesbrough issued a statement on Friday demanding Southampton's expulsion from the final, describing it as "the only appropriate response" to the scandal that has shaken English football.
The club, defeated in extra time during Monday's semi-final, has handed over evidence to league officials and expressed frustration at being excluded from the upcoming hearing.
Their statement argued that Southampton's actions violated "sporting integrity and fair competition" and called for a sporting sanction rather than merely a financial penalty.
"We remain hopeful that the EFL, as regulator, will pursue such a sanction to protect the integrity of the game, safeguard all member clubs, and deter any attempt in the future to obtain an unfair and unlawful advantage in pursuit of promotion to the Premier League," the club said.
Middlesbrough's players returned to training on Thursday still uncertain whether their season may yet be revived as the Championship's escalating "spygate" controversy continues to cast doubt over the play-off final | GETTYHull manager Sergej Jakirovic has urged the EFL to ensure the final takes place as planned on 23 May, warning that any delay poses risks to his players.
The Bosnian coach raised concerns about the demanding schedule his squad has already endured, having played two semi-final legs within three days before facing a 12-day wait for Wembley.
"The game must be Saturday," Jakirovic said. "Because how can I keep focus and concentration for the players if they will postpone this game?"
He argued the current format creates dangerous conditions for players, particularly at the end of a gruelling season.
"Because to play [the second leg] on the third day [after the first leg], it's very, very dangerous, especially at the end of the season," he added.
Jakirovic confirmed his team is preparing to face Southampton at Wembley, though he acknowledged the situation could change depending on the EFL's decision.
Southampton's place in the play-off final is under threat | REUTERS"We are preparing for Southampton in the final because they won against Middlesbrough. Then we will see. Maybe they will change something, God knows!" he said.
The Hull boss admitted he was unaware of the spying allegations before his side's first semi-final leg against Millwall.
"Before the first leg, I didn't know about this spy affair, spygate, whatever. I said: 'Why are they doing this because I know everything about Southampton because we played them two times already?'" Jakirovic explained.
He accepted that regulations must be followed but insisted his attention remains firmly on getting his squad ready for the biggest match of their season.