Southampton’s head coach, Tonda Eckert, insisted the club are taking allegations of cheating “very seriously” after they advanced to the Championship playoff final against Hull at Middlesbrough’s expense amid the backdrop of so-called spygate.

Shea Charles’s 116th-minute cross-shot sealed victory in extra time to earn a place in the Wembley showpiece on 23 May, but Southampton face the prospect of punishment from an independent disciplinary commission after being charged with breaching two counts of the English Football League’s regulations.

A visibly emotional Kim Hellberg accused Southampton of “disgraceful” behaviour after Middlesbrough’s defeat as tensions escalated. The head coach reiterated that Boro believe a financial punishment would be inadequate.

At one point, after Luke Ayling reported a discriminatory comment made by Southampton’s captain, Taylor Harwood-Bellis, Eckert appeared to move towards Hellberg on the touchline, only to be separated by the fourth official, Tom Nield, though Hellberg played down the incident between the head coaches.

Eckert conceded the matter overshadowed the tie. “It’s not easy for me to not comment, there’s just nothing I can say at the moment because it’s an ongoing investigation. We are taking the matter very seriously. I will say something, but I just cannot say it now. When the investigation is closed I will say something.”

Pressed why he hasn’t elaborated on the matter, the 33-year-old German said: “Because it’s an ongoing investigation. It’s not easy for me.”

Hellberg pulled up a reporter when they used the word “alleged” in their questioning about the incident that occurred at Boro’s Rockliffe Park base. Boro believe they caught an analyst hiding after recording and logging footage at the beginning of their training session. Hellberg confirmed he had not spoken to Eckert about the incident. “I have nothing to say to him … what should I say to him?”

“If we didn’t catch that man [the alleged analyst] who they sent up, five hours to drive, you would sit here and say ‘well done’ maybe in the tactical aspects of the game and I would go home and feel like I have failed in that aspect that I had to help my players,” Hellberg said.

“But when that is taken away from you, when someone decides: ‘Nah, we’re not going to watch every game, we’ll send someone instead, we’ll film the session and see everything, and hope they don’t get caught’ – I guess that’s why they were switching clothes and all those things – it breaks my heart, in terms of all those things I believe in. I don’t care if there are different rules in other countries.”

Hellberg added: “If we didn’t catch the person, I’d be sitting here thinking I should’ve done better things. We spend all that time away from family, all of our coaches trying to get a fair way to win a game of that magnitude and then people are talking [about a] fine for breaking that one that means you go again and take those people with more money

“It’s absolutely terrible and again it has nothing to do with the players of Southampton, they deserve all the credit for what they’ve done, it has nothing do with their supporters.”