Northern Ireland's Dallas, who was injured in a challenge with Manchester City's Jack Grealish during a game in 2022, has not played for club or country since.

"Over the past two years, the Leeds United medical team, along with the incredible surgeons in London, have worked tirelessly to help me recover from the injury I sustained," Dallas said in a statement.

"Sadly, despite their best efforts, and my body not progressing how we need it to, I must now accept the fact that my knee suffered irreparable damage and I will not be returning to play professional football. I am of course devastated by this news."

Dallas made 266 appearances for Leeds, helping the club earn promotion to the top flight in the 2019-20 season, and played 62 times for his country.

"Stuart is an icon of Leeds United and will always be welcome at Elland Road, his contribution will live long in the memory and he has cemented his place in history," the club said.