Burnley boss Sean Dyche insisted details of the breakdown in relations with defender Ben Gibson will remain private.
The Clarets confirmed on Wednesday that they had taken the highly-unusual step of allowing Gibson, a £15million signing in August 2018, to train with his former club Middlesbrough.
At his press conference ahead of Saturday's clash with Southampton, Dyche said: "It's quite a unique situation.
"There's a private angle to it, which will remain private, but at this time he's with Middlesbrough, training there to keep fit and stay sharp. He's still a Burnley player, though."
Gibson has made only one appearance this season and pushed for a move away from Burnley in January.
The club statement on Wednesday read: "The defender made it clear in the weeks leading up to the end of the January transfer window that he wanted to leave Turf Moor to seek regular first-team football.
"Unfortunately for the player, the club did not receive an offer it felt was acceptable and he remains contracted to the club."
On reports claiming there had been a row between the defender and Dyche's
assistant Ian Woan, the boss said: "At this stage the club statement is correct
and anything beyond that will remain private to us."
Dyche insisted he would not close the door on the possibility of Gibson returning but did not sound optimistic that would be the case.
"We'll see," he said. "It's one of those situations where we wait to see
what the next step is. For us as a club, and equally for him as a player."
Gibson is Burnley's joint record signing along with Chris Wood but, unlike the striker, he has failed to break into the first team, making just one Premier League appearance and six in all competitions in 18 months.
Dyche said he did not regret the signing, adding: "All parties come into a situation in good faith and want to be successful. It's just that's not always the case.
"I think there's a reality to everyone's journey in football. Some work like hand in glove, some need work, some take time. Not every player can play, you can only pick 11 players, and it's tough.
"We've got good players here en masse, and we've certainly got and have had very good centre-halves, of which he's one, but he couldn't find a way into the team. Then frustration can build out the back end of that."
Burnley will aim to continue their strong recent Premier League form after wins over Leicester and Manchester United and a draw with Arsenal.
They head to St Mary's to face Ralph Hasenhuttl's Saints, who sit level on 31 points in the table with the Clarets.
Dyche said: "Of course, it's nice to gain some some momentum. It does help. It doesn't guarantee the next one but it helps bring that inner confidence back to the fore."
The Clarets will still be without striker Ashley Barnes (hernia) and winger Johann Berg Gudmundsson (hamstring) while right-back Matt Lowton (knee) is a major doubt but left-back Charlie Taylor (hamstring) should be fit.
New signing Josh Brownhill could be involved in the matchday squad for the first time.