ZURICH, May 28 (Reuters) - FIFA needs to learn from the Olympic movement's experience and become more transparent if it is to regain its credibility, the president of the International Olympic Committee Thomas Bach told delegates at the opening of the FIFA Congress on Thursday.
Bach spoke after FIFA president Sepp Blatter addressed delegates at a ceremony ahead of the main business on the agenda which begins on Friday morning.
Blatter, himself a member of the IOC, introduced Bach as "The Boss" and admitted that FIFA was ashamed and humiliated following the arrest of several leading football officials on Wednesday, and Bach echoed the gravity of the situation in his speech.
"These are sad and difficult days for FIFA," Bach said.
"These are also extremely important days for FIFA.
"But I am confident that following a way of transparency with determination, you, the guardians of football, will overcome these challenges and you will make your sport shine once again as you have done in the past.
"We know in the IOC from our own experiences 15 years ago this fight is challenging and can be very painful.
"We also know there is no other way to ensure credibility in business, in politics and society.
"Therefore I encourage you to strengthen your co-operation with the relevant authorities, to shed full light on the matters and to take all necessary measures ... in order to properly address such grave allegations."
In 1998, the IOC was caught in its own bribes-for-votes scandal involving the 2002 Salt Lake City winter Olympics. That was the catalyst that led to wholesale reforms within the organisation.
The allegations levelled against 18 individuals involved with FIFA have been raised by the United States Department of Justice and the Swiss Attorney General's office and concern money-laundering, racketeering, fraud, bribery and possible corrupt dealing over the awarding of the 2018 and 2022 World Cup finals to Russia and Qatar.
Seven FIFA officials were arrested in a dawn raid at the luxury Baur au Lac hotel in Zurich on Wednesday with all seven facing extradition to the United States.
Ueli Maurer, the Swiss sports minister, said Wednesday's events could represent a positive turning point for FIFA.
"Regarding yesterday's events, our justice authorities are pursuing a criminal complaint filed by FIFA against persons unknown regarding the allocation of World Cups," he said.
"These proceedings will now take their due course but Switzerland strongly condemns any form of corruption.
"FIFA has a credibility problem but yesterday will go down as a good day in FIFA's history if the organisation uses it to finally put its house in order.
"Football and young people need role models and FIFA is not fulfilling that role at the present time."
Editing by Giles Elgood