Sepp Blatter's 12-year reign as president of Fifa could be challenged by one of his vice-presidents next year.

Chung Mong-Joon, from South Korea, told the Leaders in Football conference in London on Thursday that he would consider standing against the Swiss incumbent.

"I have not thought of doing so before seriously but now I will think about it," he said.

"It's still too early to say there will be no contender next May. In order to keep a large organisation like Fifa healthy you need healthy competition."