Sepp Blatter was preparing for the FIFA presidential election with world soccer reeling from the arrest of several officials and a key sponsor threatening to cut ties with the scandal-tainted organization.

In the two-pronged criminal investigations, Swiss prosecutors on Thursday were planning to question 10 members of the FIFA executive committee who voted on the awarding of the 2018 and 2022 World Cups. Separately, seven soccer officials remained in custody in Zurich as part of an American investigation into soccer corruption.

The officials were all in Zurich for the FIFA Congress, which will see Blatter challenged by Prince Ali of Jordan for the presidency on Friday. The gathering of the 209 soccer nations starts later Thursday but European body UEFA was still deciding whether to boycott the congress over the worst scandal in FIFA's 111-year history.

Visa became the first sponsor to warn that it could pull out of its FIFA contract, which is worth at least $25 million a year.

The credit card company is demanding immediate steps by FIFA aimed at "rebuilding a culture with strong ethical practices in order to restore the reputation of the games for fans everywhere."

"It is important that FIFA makes changes now, so that the focus remain(s) on these going forward," Visa said in a statement. "Should FIFA fail to do so, we have informed them that we will reassess our sponsorship."

The English Football Association, which has been at the forefront of opposition to Blatter for years, hopes other sponsors issue warnings as strident as Visa's.

"This is about one thing: How do you re-build the reputation of FIFA and turn it into an open, fair and honest organization with Blatter still at the helm," FA chairman Greg Dyke said. "It will be interesting to see how many other sponsors come out and say things like that (Visa)."

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