The world soccer players' union, FIFPro, will urge its members to boycott the 2022 World Cup if it is played in Qatar's summer, vice-president Philippe Piat said on Tuesday.
"We will not play in the summer in Qatar," Frenchman Philippe Piat, the only candidate in next week's FIFPro presidential election, said.
"Playing in Qatar when it's 45-50 degrees Celsius is not serious, even if they install air conditioning in the stadia.
"It's not serious and not only for the 22 players. There are other people involved. We have informed UEFA and FIFA that we would not play in the summer.
"We prefer to make our threat now so they won't be able to say they had not been warned."
Soccer's world governing body FIFA has set up a consultation process to decide when the tournament should be played after concerns were expressed about Qatar's fierce heat during the World Cup's traditional June-July slot.
Qatar were awarded the 2022 World Cup at the expense of rival bids from the United States, Australia, Japan and South Korea.
"We could play it in the winter, that would be all right," said Piat.
FIFA president Sepp Blatter has already paved the way for a winter World Cup after admitting he had not taken the heat problem sufficiently into consideration when the tournament was awarded to Qatar in December, 2010.
"The World Cup must be a festival of the people. But for it to be such a festival, you can't play football in the summer," he said last July.
Piat also expressed concern about the 2018 World Cup, which will be held in Russia.
"There is no freedom of speech and no local players' organisation so it is not easy to discuss with the authorities," he said.
"Playing in the summer is also a concern there but we can't really complain about it. But with Qatar, we're reaching another level."