Three senior Olympic Council of Ireland officials, including one from Northern Ireland, have had their passports, phones and laptops seized in Brazil.
It is part of the investigation into alleged illegal ticket sales.
Reports say the officials include OCI chief executive Stephen Martin – an Olympic gold medal winner – from Bangor, County Down.
The OCI has appointed a crisis management committee to lead its response to Brazil.
Mr Martin, a former hockey player, was previously a director of coaching at Ulster Hockey.
The two other executives are reported to be OCI Secretary General Dermot Henihan and Kevin Kilty, Ireland’s Olympic chef de mission.
No arrests were made during the search on Sunday.