FIFA's questioned the idea of the football World Cup being co-hosted in its technical reports on the four bids for the 2018 tournament.
The Spain/Portugal and Belgium/Netherlands bids have been criticised in FIFA's reports for being joint efforts, the BBC says after it obtained a copy of the executive summary.
Russia's bid has been criticised over transport and technology infrastructure while England's bid was criticised over training venues and team hotels, it added.
FIFA's due to make the reports on the four bids public tomrrow and will choose the 2018 hosts in two weeks when it'll also decide who'll stage the 2022 event with Japan, South Korea, United States, Australia and Qatar the candidates.
