FIFA President Sepp Blatter leaves after his statement during a news conference at the FIFA headquarters in Zurich, Switzerland, June 2, 2015. [Photo/Agencies]

ZURICH/NEW YORK - Sepp Blatter rocked the world of soccer on Tuesday by unexpectedly saying he would step down as FIFA president in the wake of a corruption investigation that reportedly may include the embattled chief himself.

Citing sources familiar with the case, The New York Times and ABC News reported on Tuesday that Blatter was being investigated by the Federal Bureau of Investigation and US prosecutors. Blatter has not been charged with any wrongdoing.

Blatter, 79, announced his decision to step down at a hastily arranged news conference in Zurich, six days after police raided a hotel in the city and arrested several FIFA officials, and four days after he was re-elected to a fifth term as FIFA president.

Blatter said an election to choose a new president would be held as soon as possible, though a FIFA official said it would probably not take place until at least December.

"FIFA needs profound restructuring," said Blatter, a Swiss national who has been a dominant presence at FIFA for decades.

"I decided to stand again to be elected because I was convinced it was the best option for football.

"Although the members of FIFA gave me a new mandate, this mandate does not seem to be supported by everyone in the world."

Blatter's decision to step down as the growing scandal plunges FIFA further into the worst crisis in its history was welcomed by his most prominent critics.