Qatar’s bid to host the 2022 World Cup could pose a potential health risk because of scorching midsummer heat, despite proposals for cooling the stadiums, world football’s governing body said.

Fifa also warned size could be a worry in the United States, Australia and Russia, as it published its technical evaluation of bids to host both the 2018 and 2022 World Cups.

The report expressed concerns that television income could be reduced if the 2022 tournament was held in the Far East or Australia.

In addition, Fifa questioned the idea of co-hosting, which is integral to the Spain/Portugal and Belgium/Netherlands bids for 2018.

“We feel we have accomplished our work in the spirit of integrity, objectiveness and transparency,” Harold Mayne-Nicholls, the Chilean who led the inspections, said in an introduction to his team’s report.

The six-member technical panel aimed to highlight concerns after making four-day visits to each bid team between July and September, which included helicopter tours and formal political dinners.

The assessments highlight legal, commercial and organisational risks that Fifa could face by entrusting a bidder with the tournament that earns Fifa about 95 per cent of its income every four years.

England, Belgium/Netherlands, Spain/Portugal, and Russia are bidding to host the 2018 World Cup, while Qatar, US, Japan, South Korea, and Australia and are candidates for 2022.

Fifa’s executive committee will choose both hosts in Zurich on December 2.

England’s bid appeared to emerge almost unscathed from the report, receiving only minor criticism over training venues and team accommodation, which also applied to a number of other bids.

South Korea also looked in good shape, apart from concerns with television rights which were shared with Australia and Japan.

“There is a risk of a reduction in TV income from Europe. The income from Asia/Oceania would need to be increased substantially to offset the likelihood of loss of revenue in Europe,” Fifa said.

However, it is not clear how much influence the technical reports have because bids are allowed to lobby executive committee members, something which could play a key role.

The reports were published the day before Fifa’s ethics committee was due to announce its verdict on two executive committee members – Reynaldo Temarii and Amos Adamu – who have been provisionally suspended over allegations they offered to sell their votes.

Fifa is also investigating allegations of collusion between unnamed bids.

Fifa’s summary of Qatar’s bid began with praise for its green credentials and “novel approach” but mentioned holding the World Cup in such a small country could be a problem.

“The fact that ten out of the 12 stadiums are located within a 25-30 km radius could represent an operational and logistical challenge,” Fifa’s technical report said.

“Any delay in the completion of the transport projects could impact Fifa’s tournament operations. Moreover, it appears to be difficult to test a transport concept prior to the event under conditions comparable to the World Cup.”

“The fact that the competition is planned in June/July, the two hottest months of the year in this region, has to be considered as a potential health risk for players, officials, the Fifa family and spectators, and requires precautions to be taken,” the report said.

Hassan Al-Thawadi, chief executive of Qatar 2022, said in a statement: “The precautions referred to in the report have already been put in place with our proposed air-cooled solutions for stadiums, training sites, fans zones and other outdoor areas.

“These are already operational in Qatar, and are being further developed and rolled out in the coming years,” Al-Thawadi said.

“As part of our legacy, we will share our new zero-carbon cooling technology with the rest of the world, ensuring that football can be played 365 days a year, no matter what the climate.”

On Russia, Fifa said: “The country’s vastness … coupled with the fact that the high-speed railway network is limited … would put pressure on the air traffic infrastructure, potentially causing transfer challenges in view of the lack of alternative means of long-distance transport.”

A Russian statement said the problems “are already being addressed and will all be solved well ahead of the 2018 World Cup.”

The Fifa reports also said the United States and Australia were over-dependent on air transport.

On the joint bids, the reports used the same phrasing: “A co-hosting concept could pose challenges regarding the joint-operational delivery of the World Cup in terms of ensuring consistent standards and implementation in various areas such as legal, IT, frequencies, safety and security.

Australia, England, South Korea, Qatar, Russia and Spain/Portugal were seen as having a low legal risk for Fifa, while the others were classed as medium-risk.