Bolton Wanderers' Lee Chung-Yong controls the ball during their FA Cup semi-final soccer match against Stoke City in London. (Reuters File Photo)

South Korea midfielder Lee Chung-Yong will be out of action for nine months after breaking his leg in a pre-season friendly playing for English Premier League side Bolton.

The 23-year-old international had to be stretchered off during the first half of the game against Newport County.

It was later confirmed that he had undergone a successful operation to repair a double fracture of his lower right leg.

"We will make sure Lee gets all the support he needs," Bolton boss Owen Coyle told the club website.

"Now it is all about his recovery and his well-being, that is the most important thing. The operation went well and we would like to pass on our thanks to the medical staff involved."

Lee was left in agony following a challenge from Newport midfielder Tom Miller and, after several minutes' treatment from paramedics, he was carried from the pitch with his right leg strapped in a brace.