Spanish daily El Mundo made the sensational claim about the roving-eyed football chief and Cristiano Ronaldo's ex girlfriend in a piece published yesterday titled 'All the women in Blatter's life.'
It declared the 79-year-old 'had a relationship' with the Russian beauty after dating tennis player Ilona Boguska but before meeting glamourous Linda Barras, 50.
Blatter began seeing Polish-born Ilona, a friend of his daughter Corinne, in 1995 and they separated in 2002, it is claimed.
They dated again after Blatter's short 2002 marriage to Graziella Bianca - a dolphin trainer who was also a friend of his daughter.
Blatter is understood to have become close to Swiss socialite Barras at the beginning of 2014 and has been described as her boyfriend by Swiss and other international press even though her husband Christian insists they are just 'close friends.'
The article linking Blatter to Shayk was written by El Mundo's Berlin-based correspondent Rosalia Sanchez.
She said today following the international repercussions of her piece that the Russian had been named by a 'Swiss source' while she was investigating the outgoing FIFA chief's love life.
El Mundo's claims about Blatter and Shayk - a guest of Prince Charles at a recent Buckingham Palace party - were being echoed across the world today.
Headlines about the supposed affair appeared on news sites as far afield as Peru, Portugal, Mexico and Vietnam as well as on social networking sites including Twitter.
A New York-based spokesman for Irina Shayk said: 'The rumours regarding an alleged romantic and/or personal affair with Sepp Blatter by El Mundo newspaper in Spain is a pathetic attempt at defaming Ms Shayk and are absolutely not true.
'We have no intentions of further acknowledging these allegations as they are wholly unfounded.'
Read full story HERE