The official told Reuters the IOC had not been asked to provide information but took the initiative, with its lawyers meeting officials investigating the case which has centred around suspended senior IOC member Patrick Hickey.
In a letter sent to all its members, the IOC said it was "actively cooperating" with authorities.
"We have already sent to you a note last week on our colleague and IOC Executive Board member Patrick Hickey who has to remain in Brazil pending an investigation into the sale of tickets for the Olympic Games Rio 2016," the letter said.
"The IOC, even though not having been officially requested by the Brazilian judicial authorities, but learning from the media about the case, has taken the initiative to cooperate with the judicial authorities and is in contact with them to shed full light on the matter."
Hickey, who was also the head of the Olympic Council of Ireland (OCI), was released from Rio's Bangu 10 maximum security prison last month but must remain in Brazil until the case is heard.
He was arrested on Aug. 10 at a luxury beachfront hotel during the Rio Games. His arrest was in connection with an investigation into an illegal ticket-scalping ring.
Police accused Hickey, 71, of leading the operation with PRO10 to funnel tickets for the Rio Games through THG Sports to raise 10 million reais (2.30 million pound) after jacking up prices. All involved have denied wrongdoing.
A Rio de Janeiro court last week accepted prosecutors' charges against Hickey, Kevin Mallon, a director of THG, and nine others.
Martin Burke, the Irish council's sports director, four other THG officials and three from Dublin-based PRO10 Sports Management, Ireland's official Olympic Games ticket reseller, were also indicted in the court document.
Except for Hickey and Mallon, all are outside the country and are now considered fugitives. All involved deny any wrongdoing.
Authorities told Reuters last week that they believe the ring had operated for around eight years and was preparing for other Olympic events such as the 2020 Tokyo Summer Games.
The ring appears to have operated at the Sochi 2014 Winter Olympics and the 2012 London Games, Rio police investigators said.
(Reporting by Karolos Grohmann, editing by Alan Baldwin)
