Olympic pole vault champion Katerina Stefanidi said athletes were being forced to take health risks as competitors started to speak out about holding the Tokyo Games during the coronavirus crisis.
Stefanidi and British heptathlete Katarina Johnson-Thompson both voiced concerns after the International Olympic Committee said it was "fully committed" to running the Games as scheduled from July 24.
An IOC member called the body's stance "insensitive and irresponsible", saying athletes were facing "anxiety and heartbreak" as they try to train during the virus emergency.
Stefanidi, one of Greece's most prominent athletes, was scheduled to hand the ceremonial flame to Japanese officials before the Greek leg of the torch relay was scrapped over COVID-19.
"The IOC wants us to keep risking our health, our family's health and public health to train every day?" she tweeted.
"You are putting us in danger right now, today, not in 4 months."
On Tuesday, minutes before the IOC statement, the Euro 2020 football tournament was delayed for a year, bowing to the crisis that has paralyzed Europe and drastically curtailed international travel.
Olympic qualifying tournaments are among the swathe of sports events that have been cancelled or postponed, with only 57 percent of athletes booking their places so far.
"It's unbelievable," said Stefanidi. "What about team sports that have to train together? What about swimming? What about gymnastics that they touch the same objects?
"There is zero consideration of the risk they are putting us in right now."
Johnson-Thompson, the world heptathlon champion, criticized the IOC for telling athletes to train "as best they can", saying it was at odds with stringent government health measures.
"I feel under pressure to train and keep the same routine which is impossible," she wrote on Twitter.
"It's difficult [to] approach the season when everything has changed in the lead-up apart from the ultimate deadline," added the Briton.
'Bigger than the Olympics'
Doubts are increasingly being expressed about holding the Olympics on time, after the outbreak that first exploded in China spread to Asia and then worldwide, infecting almost 200,000 people and killing 7,900.
On Wednesday an Olympic gymnastics qualifier in Tokyo, doubling as a test event, became the latest competition to be cancelled.
A day earlier, the deputy head of Japan's Olympic committee said he had tested positive for coronavirus.
But the IOC insisted "there is no need for any drastic decisions at this stage" adding that "any speculation at this moment would be counter-productive".
Hayley Wickenheiser, a Canadian IOC member with four ice hockey gold medals, warned "this crisis is bigger than even the Olympics".
"From an athlete perspective, I can only imagine and try to empathize with the anxiety and heartbreak athletes are feeling right now," she said in a statement.
"The uncertainty of not knowing where you're going to train tomorrow as facilities close and qualification events are cancelled all over the world would be terrible if you've been training your whole life for this."
Wickenheiser added: "I think the IOC insisting this will move ahead, with such conviction, is insensitive and irresponsible given the state of humanity."
Middle-distance runner Jess Judd also criticized the IOC advice on training, while fellow British track athlete Guy Learmonth has told The Guardian that the Olympics should be postponed.