"I personally think that in the end the 2022 World Cup will not take place in Qatar," the German told Sport Bild on Monday.
"Medics say that they cannot accept responsibility with a World Cup taking place under these conditions," the former German football (DFB) chief, who is now a member of the world soccer's governing body FIFA that awarded the tournament to Qatar in 2010.
Although wealthy Qatar has insisted that a summer World Cup is viable thanks to cooling technologies it is developing for stadiums, training areas and fan zones, there is still widespread concern over the health of the players and visiting supporters.
"They may be able to cool the stadiums but a World Cup does not take place only there," Zwanziger said.
"Fans from around the world will be coming and traveling in this heat and the first life-threatening case will trigger an investigation by a state prosecutor.
"That is not something that FIFA Exco members want to answer for."
FIFA officials, contacted by Reuters, said Zwanziger was not giving the view of the all powerful Executive Committee.
"He is expressing a personal opinion and he explicitly says so," FIFA spokeswoman Delia Fischer said. "We will not comment on a personal opinion."
FIFA President Sepp Blatter said in May that awarding the World Cup to Qatar was a 'mistake' and the tournament would probably have to be held in the European winter.
"Of course, it was a mistake. You know, one comes across a lot of mistakes in life," he told Swiss television station RTS in an interview at the time.
"The Qatar technical report indicated clearly that it is too hot in summer, but the executive committee with quite a big majority decided all the same that the tournament would be in Qatar," he added.
FIFA is now looking to shift the tournament to a European winter date to avoid the scorching summer where temperatures routinely rise over 40 Celsius.
Asian Football Confederation (AFC) president Sheikh Salman Bin Ebrahim Al Khalifa chaired a meeting to discuss the matter earlier this month with the options of January/February 2022 and November/December 2022 offered as alternatives to June/July.
However, talk of a potential change away from the usual dates has resulted in plenty of opposition from domestic leagues around the world, worried the schedule switch would severely disrupt them.
Both FIFA and Qatar World Cup organizers have also been fending off questions of corruption ever since they were awarded the tournament back in 2010, while Qatar has also been criticized for the conditions provided for migrant workers' in the tiny Gulf state.