ZURICH (AFP) - Suspended Fifa president Sepp Blatter pleaded his innocence before world football ethics judges on Thursday as Switzerland said it has frozen tens of millions of dollars in suspect accounts linked to football corruption.

Blatter, who with vice-president Michel Platini faces a long suspension, arrived and exited Fifa's Zurich headquarters in a black Mercedes, accompanied by his lawyer, and made no comment to dozens of reporters assembled outside.

But, after the hearing which lasted more than eight hours, Blatter's Virginia-based lawyer, Richard Cullen, issued a statement calling for an acquittal.

"President Blatter looks forward to a decision in his favor, because the evidence requires it," Cullen said in an e-mail sent to AFP.

"President Blatter behaved properly and certainly did not violate Fifa's Code of Ethics. This investigation should be closed and the suspension lifted," Cullen added.

Before the hearing, Blatter, 79, wrote a letter to Fifa's 209 members calling the Fifa ethics commission's investigators "the inquisition".

As the hearing went ahead, Russia's President Vladimir Putin, whose country will host the 2018 World Cup, said Blatter should be a Nobel Peace laureate.

"That is someone who should be given the Nobel Peace Prize," Putin said. "His contribution to the global humanitarian sphere is colossal."

Blatter is under criminal investigation in Switzerland over a two million Swiss francs (S$2.8 million) payment made to Platini in 2011 for work carried out about a decade earlier.

Platini's case will be heard on Friday, but he has said he will boycott the tribunal. His lawyers will go however.

Platini has claimed the verdict has been decided in advance and his lawyers say Fifa's ethics committee has recommended a life ban for the French football legend.

Blatter and Platini deny any misconduct.

The ethics committee chamber is expected to announce its verdict next Monday. Appeals to a Fifa appeal committee and the Court of Arbitration for Sport are then possible.

Fifa has been plunged into several corruption scandals this year which played a key role in Blatter's announcement in June that he would stand down when a new election is held in February.

After a year of unprecedented scandal, Fifa's acting president Issa Hayatou and the body's acting secretary-general Markus Kattner warned that the storm engulfing world football may not be over.

"There may be further challenges ahead," the two said in an open letter which reviewed a reform package introduced last month aimed at restoring Fifa's credibility.

"It will take time for these reforms to take effect, but our resolve to rebuild Fifa for the better remains steadfast," the letter added.

Platini was considered favourite to take over from Blatter but his campaign has been frozen since he and Blatter were suspended in October over the payment which they insist was legal.

The United States asked Switzerland to freeze about 50 accounts in Swiss banks linked to its massive inquiry into football corruption, a federal prosecution spokesman told AFP.

Federal justice spokesman Folco Galli said "funds in the high tens of millions (Swiss francs) are blocked."

The Tages Anzeiger newspaper said the figure was between 50 million and 100 million Swiss francs. Galli declined to comment on the total.

The action involved about 50 accounts in 10 Swiss banks. Numerous Fifa members are known to have accounts in the country.

Nicolas Leoz, a longtime head of the South American confederation, Conmebol, had 12 accounts in Switzerland, the Swiss television programme Eco said, quoting details from the US request.

The United States has charged 39 individuals, including Leoz, and two companies over bribes of more than $200 million paid for football marketing and television rights deals.

Twelve have so far pleaded guilty.

Galli said that because of the scope of the US inquiry, the Fifa case is "one of the biggest cases of foreign help that we are dealing with."

The UBS, Credit Suisse, Pictet, BSI and Julius Baer banks have all received requests for account details.

The federal justice office looks at each request case by case and if suspicious information is confirmed hands details to the United States.

But appeals are possible against the decisions and Tages Anzeiger said it could take years to get all the cases completed.

Germany has also asked Switzerland for judicial help over its inquiry into allegations that bribes were paid to secure the 2006 World Cup finals.