Russia's president has backed the leadership of Sepp Blatter, FIFA's president, a day after world football's governing body was engulfed in controversy by the prospect of twin criminal corruption investigations in the US and Switzerland.
Vladimir Putin's support for Blatter came as the FIFA leader cancelled a public appearance at a medical conference in Zurich and major international sponsors threatened to pull their support.
"This is clearly an attempt to block the reelection of Blatter as president of FIFA and is an extremely serious breach of the principles of how international organisations work," Putin said in televised comments broadcast on Thursday.
Swiss authorities announced on Wednesday that it had launched a criminal investigation into the bidding contest for the 2018 and 2022 World Cups - set to be held in Russia and Qatar.
Almost simultaneously, the US Department of Justice indicted nine FIFA officials and five associated officials on corruption charges, with Swiss authorities arresting seven of the officials in Zurich where FIFA is due to hold its congress.
Putin was highly critical of US involvement in FIFA affairs on Thursday.
"This is yet another blatant attempt [by the US] to extend its jurisdiction to other states," Putin said.
Blatter missed giving a scheduled speech to open a session of FIFA's medical conference in a Zurich hotel on Thursday.
Jiri Dvorak, FIFA chief medical officer, told delegates that Blatter has to "manage the situation", referring to the corruption crisis.
Swiss authorities said there were no plans yet to question Blatter in their investigation.
On Wednesday, Blatter responded to the arrest of top officials from the sport's governing body by insisting it showed his efforts to eradicate corruption were working.
The deepest crisis in FIFA's 111-year history is threatening Blatter's bid to win a fifth, four-year term in a contest against Prince Ali bin al-Hussein of Jordan on Friday, with European football leaders trying to delay the election.
Visa became the first sponsor to warn that it could pull out of its FIFA contract, which is worth at least $25m a year.
German sportswear company Adidas, long associated with FIFA, said the football body should do more to establish transparent compliance standards.
Anheuser-Busch InBev, whose Budweiser brand is a sponsor of the 2018 World Cup, said it was closely monitoring developments.
Coca-Cola Co, another FIFA sponsor, said the charges had "tarnished the mission and ideals of the FIFA World Cup and we have repeatedly expressed our concerns about these serious allegations".
Those arrested in Zurich on Wednesday include Jeffrey Webb and Eugenio Figueredo, FIFA vice presidents who were among 11 people provisionally suspended from world football by the body.
Former executive committee members Jack Warner, Nicolas Leoz and Chuck Blazer were suspended despite no longer being involved in the game.
The others are Eduardo Li, Costa Rican football federation president; Rafael Esquivel, Venezuela FA chief; Jose Maria Marin, former Brazilian FA chief; Costas Takkas, who works for CONCACAF head Webb; Julio Rocha, FIFA development officer; and Warner's son Daryll.