Kevin Pietersen has confirmed his retirement at the age of 37, citing fitness concerns among his reasons for walking away from cricket.

Pietersen appeared to announce he was quitting the sport with a social media post on Friday that read: "BOOTS UP! Thank you!"

And the South African, who represented England at international level, has now confirmed the Pakistan Super League was his final tournament.

Quetta Gladiators advanced to the play-offs and play Peshawar Zalmi in an eliminator on Tuesday, but Pietersen will not be playing.

"I've had enough," Pietersen told ITV. "Twenty overs of fielding feels like playing a Test match, so it's time to hang up the boots.

"I've got better and bigger things to go on to now. I've had a wonderful career but I just don't think I've got it in me to keep improving or try to improve."