The Spain-Portugal and Qatar World Cup bids are under investigation by Fifa's ethics committee following allegations that they agreed to trade votes in clear breach of bidding rules, The Daily Telegraph can disclose.
Sources with knowledge of the investigation confirmed on Wednesday night that the two bids are the subject of an inquiry launched in the wake of corruption allegations against two Fifa executive committee members.
If found guilty of colluding, the bids could face expulsion from the contest for the 2018 and 2022 tournaments. Spain-Portugal is campaigning to win the 2018 race, with Qatar among five candidates for 2022.
The investigation into alleged collusion has the potential to blow the race for the two tournaments wide open, with Spain-Portugal a major rival to England's bid for the 2018 tournament.
Were the Iberian bid to be reprimanded or ejected, England would face a straight fight with frontrunners Russia. Holland-Belgium is considered the outsider of the four European bids.
Confirmation of the investigation into the bids came as Fifa suspended Amos Adamu and Reynald Temarii, the two executive committee members exposed in the Sunday Times' cash-for-votes revelations last weekend.
After a meeting of Fifa's ethics committee in Zurich on Wednesday, at which they both appeared, the pair were provisionally suspended from all football-related activity pending the outcome of an investigation that is expected to conclude in mid-November.
"The decision to suspend these two individuals was taken unanimously," said Claudio Sulser, chairman of the ethics committee.
"The ethics committee has zero tolerance for anything that violates its code of ethics in order to protect the good of Fifa and its image," he said. "We deem that it is crucial to protect the integrity of the 2018 and 2022 World Cup bidding process."
In a statement, Fifa said that a provisional suspension was justified "taking into account the gravity of the case and the likelihood that a breach of the Fifa statutes, code of ethics and disciplinary code has been committed".
Former Nigerian sports minister Adamu was filmed by the Sunday Times suggesting to undercover reporters that a payment of £500,000 to build artificial pitches be directed through a relative's bank account.
Temarii, president of the Oceania Football Confederation, was recorded discussing a £1.5 million payment to improve a football development centre in New Zealand. He also told the reporters that two bids had offered "huge" payments for his support and that he had received offers of between $10-12 million (£7.5 million).
Four other officials implicated in the Sunday Times expose were also suspended. Slim Aloulou, chairman of Fifa's disputes resolution committee, Amadou Diakite, a member of the referees committee, Ahongalu Fusimalohi and former executive committee member Ismael Bhamjee all now face a full investigation.
Fifa general secretary Jerome Valcke said that the vote on the World Cup was unlikely to be delayed beyond the scheduled date of Dec 2, but neither he nor Susler was able to say whether it could go ahead if Adamu and Temarii remain suspended.
Their suspension lasts for 30 days and can be extended for a further 20, but Sulser said he was confident that the investigation would be completed, with an announcement due between Nov 15-17.
Sulser said he hoped to conclude the collusion inquiry into Spain-Portugal and Qatar at the same time. Neither bid was at Wednesday's meeting, though Fifa president Sepp Blatter did meet with the Emir of Qatar in Zurich on Wednesday in a long-standing arrangement.
The Daily Telegraph revealed in September that rumours of collusion between Spain-Portugal and Qatar were widespread in football.
The central charge is that the two bids agreed to trade blocs of votes under their influence, with Qatar's supporters on the executive committee alleged to have agreed to back Spain-Portugal in the 2018 vote in exchange for support from the Iberian's voters in the 2022 race.
"We got the information [about collusion] a few weeks ago, and there have been rumours saying that it definitely took place," said Valcke. "We said that we should ask the ethics committee to look at the case."
The collusion inquiry will be greeted with delight by Spain-Portugal and Qatar's rivals, but it will also raise questions about the wisdom of running the 2018 and 2022 races in parallel.
Valcke defended that decision: "The process for 2018 and 2022 has been perfectly well managed and the ethics committee has made several interventions to make sure that the bids are complying with the rules."
He rejected suggestions that the allegations against Adamu and Temarii showed that Fifa is corrupt.
Blatter said the investigation marked a "sad day for football" adding: "As the president of Fifa, I appeal to all members of the Fifa family to behave in an honest, sincere and respectful manner because football is based on discipline, respect, fair play and solidarity.
"I am a little bit surprised that [you] say is Fifa corrupt? Fifa is actually in the world of sport a well-recognised organisation and institution, so let us do our job and clarify the situation and bring back credibility to football.
"Our society is full of devils and you find these devils in football. We have to fight for fair play. Trust us and you will see confidence will be restored."