The International Amateur Athletic Federation (IAAF) have warned that they may have to take radical steps to protect the "exclusivity" of the World Championships if football's World Cup finals become a biennial tournament.

If FIFA president Sepp Blatter's proposal to stage the World Cup every two years instead of four becomes reality, the World Championships could be moved from odd years to even years to prevent any clash.

IAAF spokesman Giorgio Reineri confirmed: "The IAAF could change the year so as not to clash with the World Cup."

That would see the World Championships, the biennial event which takes place in Seville this year between August 20th-29th, clashing with the summer Olympics once every four years.

And even though the World Championships are considered the third biggest sporting event behind the Olympics and the World Cup, Reineri has warned the IAAF would take steps to ensure the best athletes attend the championships.

That could mean track and field's governing body restricting Olympic competition to athletes aged 23 and under - as FIFA require happens in the Olympic football tournament to safeguard the status of their World Cup.

Reineri warned: "We will protect our own championships. Only in our event should all the best athletes be present."