The world governing body has picked up on rumours that one European bidder for 2018 has made a quid pro quo agreement for blocks of votes with a country bidding for 2022.

Such deals are banned under FIFA's bidding rules and the organisation's secretary general Jerome Valcke told Bloomberg: "We will send reminders on the rules and conduct via our ethics committee.

"There are a lot of rumours around 2018/22 but I think we are monitoring efficiently what is done by the nine bidders, and we will also inform our executive committee members again at our next meeting in October about such rumours on vote-sharing and their responsibility."

England, Russia, Spain/Portugal, Holland/Belgium and the USA are bidding for the 2018 tournament, though the USA may pull out before the vote by FIFA's executive committee on December 2 to concentrate on 2022.

They face Qatar, Australia, Japan and South Korea in the contest for 2022.