Olympic Council of Ireland (OCI) president Patrick Hickey has temporarily stepped aside from his official functions after a warrant was issued for his arrest by Brazilian authorities.
Reports in the Brazilian media emerged on Tuesday that Hickey, who is also the European Olympic Committee president and an International Olympic Committee member, had been arrested for passing on tickets to be re-sold at inflated prices.
The OCI has now confirmed that Hickey was sought out by authorities and received medical attention at hospital after falling ill.
A statement from the OCI read: "A warrant of arrest for OCI president Pat Hickey was issued this morning by Brazilian authorities.
"Contrary to reports, Mr Hickey complied fully with the terms of the warrant. Mr Hickey was taken ill as this warrant was served and was taken to hospital as a precautionary measure.
"In light of this morning's development and his ill health, Mr Hickey has taken the decision to step aside temporarily as President of the OCI and all other Olympic functions (IOC member in Ireland, EOC president, ANOC vice president) until this matter is fully resolved.
"Mr Hickey will of course continue to cooperate and assist with all ongoing enquiries."
It is claimed by the Brazilian media that Hickey's arrest is in connection with that of countryman Kevin Mallon, who is alleged to have passed OCI tickets to THG Sports. Mallon is a director of the company.