has plunged world soccer's governing body into the worst crisis in its history.

Blatter, who is 79, announced the decision at a news conference in Zurich, six days after

the FBI raided a hotel in the city and arrested several FIFA officials and just four days

after he was re-elected to a fifth term as president.

"Thank you so much that you are here, the interest is flowing

this wonderful day today, it was a big congress and we have the same president, I am a happy man, thank you"

FIFA, which has been ruled over by Blatter since 1998, was rocked this week by the announcement

of a US investigation into alleged widespread financial wrongdoing stretching back for years.

Swiss authorities mounted their own criminal probe into the award of the 2018 and 2022

World Cups to Russia and Qatar, respectively.

While Blatter was not mentioned in either the U.S. or Swiss investigations, there were

widespread calls for him to quit, mostly from Western nations. Some major sponsors also

expressed misgivings about the impact of the scandal.

Blatter said an election to choose a new FIFA president would be held as soon as possible.