A Qatari company closely linked to the country's successful 2022 World Cup bid reportedly paid a senior official and members of his family almost $2 million (£1.2m), The Daily Telegraph claims.
Jack Warner, the former vice-president of Fifa, appears to have been paid around £720,000 by the company after Qatar was awarded the prestigious competition, the newspaper reports.
It was also reported that the FBI is now investigating the links between the company, which is controlled by a former Qatari official, and Mr Warner.
Mr Warner strenuously denied the report and said in a statement: "I have no interest in joining in the foolishness that is now passing as news on Qatar and Jack Warner.
"Nor do I intend to join those who are on a witch hunt against the World Cup 2022 venue. And do consider this as my final comment on this matter."
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His representatives said Cassidy, who was hospitalised last week, died "surrounded by those he loved."
The company’s recently appointed Chief Executive Dara Khosrowshahi said the breach was made by two individuals outside the company.