Fifa have given all 25 Caribbean associations 48 hours to provide statements about the events at the meeting in Trinidad which led to Mohamed bin Hammam being banned for life for bribery.
The associations have been warned that "truthful and complete" reporting of the events is necessary, with anyone not coming forward facing "the full range of sanctions", which includes a life ban.
Bin Hammam, the Qatari who was bidding for the presidency of world football's governing body, was banned by Fifa's ethics committee on Saturday after being found guilty of giving or offering cash gifts of around US$40,000 (Dh147,000) each to the Caribbean Football Union (CFU) associations. He has said he will appeal.
In a statement, football's world governing body said: "Fifa has sent a letter yesterday 25 July to all CFU associations, asking the associations, their presidents, and any of their members with knowledge of anything that transpired during the meetings held on 10 and 11 May in Trinidad and Tobago, to provide and report all relevant information in their possession within 48 hours.
"Truthful and complete reporting will be considered in mitigation by the ethics committee when deciding on potential sanctions. Any person who has relevant information but does not come forward during this 48-hour period will be subject to the full range of sanctions.
"Following this 48-hour period, the ethics committee will be asked to open the necessary ethics proceedings."
All of the 25 associations from the CFU, bar Cuba, attended the meeting on May 10 and 11, where bin Hammam was speaking about his campaign to be Fifa president.
Officials from nine associations told investigators last month they were given or offered cash gifts of $40,000 each. The other 15 denied receiving any cash gifts or refused to meet investigators.
The investigation into the bribery claims was carried out by the Freeh Group International Europe, the private investigative agency owned by the former FBI chief Louis Freeh.
Four associations did not respond to invitations to meet investigators: Anguilla, Antigua and Barbuda, Dominica and Montserrat.
A further 11 associations sent officials to meet investigators but denied receiving cash gifts. They were: Barbados, Guyana, British Virgin Islands, Dominican Republic, Haiti, Jamaica, St Kitts and Nevis, St Lucia, St Vincent and Grenadines, Trinidad & Tobago and US Virgin Islands.