They face an EFL charge after allegedly spying on their training sessions.
Middlesbrough manager Kim Hellberg accused Southampton of "disgraceful" behaviour after their 2-1 defeat in the Championship play-off semi-finals.
Their opponents are facing an EFL charge for allegedly spying on their training session ahead of the first leg
Hellberg says it's "sad" that the episode damaged the tie.
Southampton will play Hull for a place in the Premier League later this month.

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