Football's world governing body had boasted that last year's tournament was the first "fully carbon neutral World Cup" to be staged.

Five countries - Belgium, Britain, France, The Netherlands and Switzerland - alleged that this was untrue to the Swiss Fair Trade Commission which has now upheld their complaint.

The judgement is not legally binding but FIFA has been advised not to repeat that Qatar 2022 was carbon neutral in the future.

A statement from the Commission said that no proof was provided to back up the claim.

It said "factual allegations must be correct by law and must not be misleading" and that a "strict standard" was required to prove environmental claims.

"In some cases, FIFA used absolute statements, thus creating the false and misleading impression that the 2022 World Cup in Qatar was already climate or CO₂ neutral before and during the tournament," the Commission said.

"It cannot be claimed that sustainability goals have been achieved until there are definitive and generally accepted methods for measuring sustainability or ensuring its implementation. 

"The burden of proof lies with the advertising company. 

"FIFA was unable to provide the proof of correctness required in the present proceedings."

A report commissioned by FIFA had reported that 3.63 million tonnes of CO₂ were expected in Qatar, but the five complaining countries said this figure was too low.

"Whether FIFA's estimate is realistic or accurate could not be conclusively assessed," the Commission added. 

"Obviously, however, there is no generally accepted method. 

"Even if the estimate should one day correspond to the definitive figures, it remained unclear whether the promised compensation was realistic at all."

FIFA has claimed that it has already offset the 3.63 million tonnes and that it will do the same for any emissions definitively calculated in the future.

But the Commission said it did not provide evidence of how it would do this and if the measures would meet Swiss standards.

"The Commission recommends that FIFA refrain from making the objectionable statements in the future," it said.

"In particular, the fact that the 2022 World Cup in Qatar will be climate neutral or CO₂ neutral.

"Unless, at the time of communication, it can provide full proof of the calculation of all CO₂ emissions caused by the tournament according to generally accepted methods on the one hand, and proof of full compensation of these CO₂ emissions on the other." 

Some sporting organisations have been accused of "greenwashing" - an attempt to claim that initiatives are environmentally friendly in exchange for positive coverage, when it might not be the case.

"FIFA is fully aware that climate change is one of the most pressing challenges of our time and believes it requires each of us to take immediate and sustainable climate action," the governing body said.

"FIFA is also fully aware of the impacts that mega-events have on the economy, the natural environment and on people and communities, and has been making substantial efforts to tackle those impacts and, at the same time, to use opportunities to maximise the positive effects of its most iconic tournament, including Qatar 2022. 

"It remains committed to continuously improve its approaches in collaboration with key stakeholders.

"In reference to the recommendation by the Swiss Fair Trade Commission, FIFA is analysing the reasons for its recommendation, which may still be appealed." 

Campaign group Carbon Market Watch (CMW) said it is "impossible" for a sporting event to credibly cancel out its carbon impact.

It said emissions associated with building new stadiums in Qatar were understated by as much as a factor of eight.

"The decision of the Swiss Fair Trade Commission confirms the findings of our research and reinforces what we have been saying for the past year - FIFA's messaging is misleading for the hundreds of millions of fans around the world who were pushed to believe that their favourite tournament has no impact on the climate," says Gilles Dufrasne, CMW’s lead on global carbon markets. 

"It's high time for this absurd greenwashing to end."