In a stunning twist just days ahead of Fifa's presidential election, football's governing body says it is investigating challenger Mohamed bin Hammam for bribery in his campaign to unseat Sepp Blatter.

Fifa has summoned bin Hammam, the Asian Football Confederation leader, and Jack Warner, Fifa's vice-president, to an ethics hearing on Sunday to face allegations of corruption in the Qatari official's presidential election bid.

The claims have been levelled by Warner's longtime Concacaf ally Chuck Blazer of the US.