The Qatar 2022 World Cup bid team have been accused of running a secret campaign in 2010 to sabotage competing host bids, according to a report published by the Sunday Times.
The paper claims to have seen leaked documents that show the Qatari bid team employed a US PR firm and ex-CIA agents to smear its rivals - mainly the United States and Australia.
The alleged aim was to create propaganda to give the impression that a World Cup would not be supported domestically. The Qatar tournament organisers deny the allegations.
Such a campaign alleged by the Sunday Times would have broken Fifa's bidding rules.
Qatar beat rival bids from the United States, Australia, South Korea and Japan to the right to host the 2022 World Cup.
Fifa's rules say World Cup bidders should not make "any written or oral statements of any kind, whether adverse or otherwise, about the bids or candidatures of any other member association".
The Qatar bid team has been previously accused of corruption, but was cleared following a two-year FIFA inquiry.
Some of the alleged aspects of the smear campaign:
A respected academic was paid $9,000 to write a negative report on the huge economic cost of an American World Cup, which was then distributed to news media around the world.
Journalists, bloggers and high-profile figures were recruited in each country to hype up negative aspects of their respective bids.
A group of American physical education teachers were recruited to ask their US Congressmen to oppose a US World Cup on the grounds that the money would be better used on high school sports.
Grassroots protests were organised at rugby games in Australia opposing the country's bid.
Intelligence reports were compiled on individuals involved in rival bids.
The documents seen by the Sunday Times - which the paper says were leaked by a whistleblower who worked on the 2022 bid team - were apparently unavailable during the Fifa inquiry.
The Qatar bid team is alleged to have employed the New York office of communications company Brown Lloyd Jones, which is now BLJ Worldwide, along with a team of former intelligence officers to run a campaign aimed at undermining one of Fifa's key criteria in the bidding process - that each bid should have strong backing at home.
In a statement Qatar's Supreme Committee for Delivery and Legacy said it "rejects each and every allegation put forward by the Sunday Times".
"We have been thoroughly investigated and have been forthcoming with all information related to our bid, including the official investigation led by US attorney Michael Garcia," it said.
"We have strictly adhered to all FIFA's rules and regulations for the 2018/2022 World Cup bidding process."