Adidas, the German maker of sportswear and equipment and a top FIFA sponsor, declined to join US companies in calling for Sepp Blatter's immediate resignation Saturday but urged reform of world football.

"As we have frequently stressed in the past, fundamental changes in the interest of football must be made," a company spokesman, Oliver Brueggen, told German news agency DPA.

"That is why the reform process that has begun must continue transparently and quickly."

In separate statements issued one week after criminal proceedings were launched against the world football chief in Switzerland, Coca-Cola, McDonald's, Visa and Budweiser all called on the 79-year-old Blatter to step down.

It marked the first time that FIFA's powerful financial backers -- who together have pumped hundreds of millions of dollars into the organisation through deals spanning decades -- had called explicitly for Blatter to resign.

In a statement issued by his US lawyer in reaction to the sponsor demands, Blatter defiantly vowed to remain in office.