The head of FIFA's audit and compliance unit said on Sunday that changes at the top of world football's governing body were "indispensable" following reports Sepp Blatter might go back on his decision to resign.

"For me, the reforms are the central topic," wrote Domenico Scala in a statement.

"That is why I think it is clearly indispensable to follow through with the initiated process of president's change as it has been announced."

Scala's statement came after Swiss newspaper Schweiz am Sonntag cited an anonymous source close to Blatter as saying he had not ruled out the prospect of going back on his decision to resign after receiving messages of support from Asian and African federations.

When contacted by AFP, FIFA and the Confederation of African Football (CAF) stuck to their official positions, that Blatter had announced his resignation on June 2 and that the CAF had taken due note.

On Thursday, the European Parliament called on Blatter to step down immediately and allow for an interim leader to launch reforms in the organisation.

But FIFA have repeated that the 79-year-old Swiss will continue in office until a successor is designated, probably by the end of the year.

An extraordinary meeting of the FIFA Executive Committee will take place in Zurich on July 20, when a date will be fixed for the congress at which Blatter's successor will be elected.

It is likely to take place between December this year and March 2016, according to the audit unit that supervises the electoral procedure.

Blatter was reelected late last month in Zurich for a fifth term as president, only three days after 14 FIFA officials and partners were charged as part of a corruption investigation led by US authorities.

But four days after that he announced his resignation.

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