Football's top body, based in Zurich, has been plagued by corruption allegations over decades but Wednesday's shock arrests were the biggest blow to its reputation so far.
"In the course of the morning, a further wanted soccer official has been arrested further to a request from the United States," the attorney-general's office said, naming a seventh man.
It said the seven officials being held were Eugenio Figueredo, Fifa vice president and executive committee member from Uruguay; Costa Rican Eduardo Li, who was supposed to join the Fifa executive committee; and Brazilian soccer federation chief Jose Maria Marin, a member of Fifa's organizing committee for the Olympic football tournaments.
The others were Nicaraguan Julio Rocha, Britons Costas Takkas and Jeffrey Webb, the FIFA vice president and executive committee member, and Rafael Esquivel, president of the Venezuelan Football Federation.
The arrests follow a US probe into a bribery and kickback scheme spanning two decades.
After the Zurich arrests, the US Justice Department announced conspiracy and corruption charges against nine FIFA officials and five business executives.
Swiss police seized documents and electronic data after raiding the Fifa headquarters on Wednesday as part of a separate investigation already underway into money laundering and fraud involving the body's awarding of the 2018 and 2022 World Cups to Russia and Qatar respectively.
The attorney-general's office said it had also "ordered the blocking of accounts at several banks in Switzerland through which bribes are claimed to have flowed as well as the seizure of related bank documents."
Fifa in a separate statement said it was "fully cooperating as injured party in the actions by Swiss authorities".
"Fifa welcomes actions that can help contribute to rooting out any wrongdoing in football," a statement said.
Meanwhile, the organization's spokesman Walter de Gregorio said that Fifa president Sepp Blatter is not involved in the corruption probes and that a presidential vote will go ahead Friday as planned.
Blatter is "relaxed" about the fallout from the controversy, De Gregorio told a press conference at Fifa headquarters.
"The general secretary and the president are not involved in this," De Gregorio said, referring to Blatter and Fifa secretary general secretary Jerome Valcke.