Dublin: Patrick Hickey, the head of the Olympic Council of Ireland, temporarily stood down from all Olympic roles after his arrest over illegal ticket sales, the OCI said Wednesday.
Hickey, 71, was arrested at his Rio hotel after being accused of ticket scalping, ambush marketing and conspiracy.
He was taken away from the hotel in an ambulance amid concerns for his health.
An OCI statement said he had stepped down temporarily as an International Olympic Committee member, president of the European Olympic Committees, vice-president of the Association of National Olympic Committees and head of the Irish national committee.
"In light of this morning's developments and his ill health, Mr Hickey has taken the decision to step aside temporarily as president of the OCI and all other Olympic functions ... until this matter is fully resolved.
"Mr Hickey will of course continue to co-operate and assist with all ongoing inquiries."
Prosecutors have estimated the profits from the alleged black market sales at $3 million dollars.
Brazilian police have launched a widening investigation after seizing more than 1,000 premier tickets for Games events, including the opening ceremony.
Tickets with a face value of about $1,000 dollars were sold for more than $8,000. Some of the tickets had the Olympic Council of Ireland name on them.
The OCI would only say that it was "seeking total clarity on the situation" before commenting.
Ireland's Sports Minister Shane Ross said he was "shell-shocked" at the news of Hickey's arrest and would be returning to Dublin as soon as possible to set up an inquiry into a controversy that has been rumbling since Brazilian police arrested an Irish businesman amid accusations of ticket-touting.
Ross told Irish national broadcaster RTE there had been "a series of shellshocks" since his arrival in Brazil to confront Hickey over the OCI's alleged involvement in the matter.
"I'm very distressed at what's been happening and Irish people have been upset by the instances that are going on have diverted from a wonderful performance by the athletes," he said.
"We are absolutely determined we will set up an inquiry to find out what happened. I don't know what the best form of inquiry is now. Events are moving too fast but we'll decide that over the next few days."
The minister said Hickey, who is believed to still be in hospital, has accepted consular assistance.
Hickey has been a member of the IOC executive board since 2012. As head of the European body he has been instrumental in setting up the European Games which was first held in Baku, Azerbaijan, last year.