UEFA President Michel Platini says a payment to him being looked into by Swiss authorities was for work carried out under contract at FIFA.

FIFA president Sepp Blatter has been questioned by Swiss federal police over alleged financial corruption. The attorney general's office in Switzerland said it has opened criminal proceedings against Blatter over possible criminal mismanagement and misappropriation of FIFA money.

The Swiss federal office said Blatter was interrogated after chairing a meeting of FIFA's executive committee on Friday. FIFA vice-president Platini was questioned as a witness over a suspected "disloyal payment" of $2 million he received from Blatter in February 2011, Swiss authorities said.

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Platini said the following in a released statement: "Today I was asked by the Swiss authorities to provide information relating to the ongoing investigations surrounding FIFA. I have always been open to supporting the relevant bodies and authorities in their investigative work and therefore co-operated fully.

"Regarding the payment that was made to me, I wish to state that this amount relates to work which I carried out under a contract with FIFA and I was pleased to have been able to clarify all matters relating to this with the authorities. Today I also made clear to the Swiss authorities that since I live in Switzerland I am available to speak with them any time to clarify any matters relating to the investigations."

The announcements came as FIFA wrapped up a two-day executive committee meeting and marked another stunning day of turmoil for the governing body and Blatter, who have been targeted by American and Swiss investigations into corruption.

Blatter, 79, is set to step down in February as a result of those probes, but the opening of formal proceedings against him could lead the FIFA ethics committee to provisionally suspend him from duty. The American probe rocked FIFA on May 27, when senior officials suspected of bribery and racketeering were arrested in dawn raids at a luxury Zurich hotel two days before Mr Blatter's re-election.

Blatter is a stated target of that case but has always denied being corrupt, blaming individuals who are outside of FIFA's control. FIFA later issued a statement saying the Swiss attorney general "conducted interviews and gathered documents pursuant to its investigation", adding that it was co-operating with the probe.

Information from The Associated Press and FOXSoccer.com's newswire services contributed to this report.