A group of world-leading scientists have warned Fifa its current heat safety measures for the men’s 2026 World Cup are “inadequate” and could put players at risk of serious harm.

In an open letter, external, international experts in health, climate and sports performance say the governing body’s guidelines are out of step with the current science and “impossible to justify”. They call on Fifa to introduce stronger protections, including longer cooling breaks and clearer protocols for delaying or postponing games in extreme conditions.

Heat is expected to be an issue at this summer’s tournament in the United States, Canada and Mexico, with researchers warning temperatures at 14 of the 16 stadiums being used could exceed dangerous levels.

In parts of the southern US and northern Mexico, average daytime highs are typically in the low to mid-30Cs and can rise towards 40C during hotter spells.

When temperature, humidity, wind speeds and the strength of the sunshine are factored in, players in these World Cup host cities are at greatest risk of experiencing extreme levels of heat stress on the body.

Fifa says it is “committed to protecting the health and safety of players, referees, fans, volunteers and staff” and that climate-related risks are assessed as part of tournament planning.