TOKYO — International Olympic Committee President Thomas Bach laid a wreath at a memorial to the victims of the 1945 atomic bombing in Hiroshima on Friday, but the spectator-free event held in the rain, with the only sound coming from the cries of distant protesters, symbolized his inability to ignite popular support for the Summer Games, which are set to begin in a week.

Preparations hit two more major snags when a Ugandan athlete went missing from a training camp in western Japan and a member of the Nigerian delegation became the first Olympic visitor admitted to a hospital with covid-19, according to reports.

Bach promised this week that there was “zero” risk of the coronavirus spreading in the Olympic Village or to the Japanese public as a result of the Games, which he billed as “the most restrictive sports event ever in the world.”

But the extensive precautions depend on athletes, officials and other visitors obeying the rules. This week, two American and two British contractors were arrested by police for suspected cocaine use during a night out in Tokyo, local media reported. Police are searching for the missing Ugandan, a weightlifter, according to broadcaster NHK.

Two Ugandans — an athlete and a coach — tested positive for the coronavirus after they arrived in Japan last month; they are among around 30 game participants and workers who have tested positive. The member of the Nigerian delegation, a nonathlete over 60, only experienced mild symptoms but was hospitalized as a precaution, TV Asahi reported.

Earlier on Friday, the Australian Olympic Committee said tennis player Alex de Minaur, ranked 17th in the world, tested positive before his departure for Japan, Reuters reported, and U.S. basketball star Bradley Beal of the Washington Wizards also will miss the Games after he entered coronavirus protocols at a training camp in Las Vegas.

In Hiroshima, Bach also visited the Peace Memorial Museum and the Atomic Bomb Dome, one of the few buildings left standing after the attack nearly 76 years ago. IOC Vice President John Coates is taking part in similar events in Nagasaki, which was struck by an atomic bomb three days after Hiroshima.

The pair are using their visits to promote the first day of the Olympic Truce, a tradition from ancient Greece that was supposed to allow competitors and spectators to travel to the Games in peace, an idea revived by the IOC and supported by the United Nations in the 1990s. Bach said Pierre de Coubertin had seen the Olympics as a way to “promote peace among nations and people” when he revived the Games 125 years ago.

“This peace mission continues to be at the heart of the Olympic Games,” he said. “Today, I am here to remember all the people who are commemorated at this very place. I am here to reaffirm our peace mission and to pay our respects to Hiroshima, as a city of peace.”

But civic groups representing pacifists, survivors of the bomb blast and opponents of the Olympics have objected strongly to Bach’s visit, arguing he is exploiting the issue of peace to justify pushing ahead with the Games despite widespread public opposition and health risks. A small group of protesters, kept well away from Bach and outside the park by police, chanted for the Olympics to be canceled and for Bach to “go home.”

“President Bach using the image of ‘a peaceful world without nuclear weapons’ only to justify holding of the Olympics by force under the pandemic is a blasphemy to atomic bombing survivors,” 11 civic groups said in a statement submitted to city and prefectural leaders this week. “An act like this does nothing but do harm to the global nuclear weapons ban movement.”

Attempts by the IOC to link itself to Hiroshima’s campaign for a peaceful, nuclear-free world have not always been so controversial.

At the previous Olympics held in Tokyo, in 1964, 19-year Yoshinori Sakai, born in Hiroshima on the day the atomic bomb was dropped, ignited the cauldron in National Stadium to open the Games. In 1994, then-IOC president Juan Antonio Samaranch visited the Hiroshima Peace Museum and wrote in the guest book: “Today Hiroshima is the ‘City of Peace.’ The Olympic Movement is also enforcing peace in the world.”

But this time around, a petition opposed to Bach’s visit to the city attracted around 75,000 signatures.

The IOC chief arrived in Japan only last week and spent his first three days in quarantine at a five-star hotel in central Tokyo. Critics say his trip to Hiroshima is setting a poor example, given rising coronavirus infections in Tokyo and last week’s declaration of a fourth state of emergency in the capital.

“For Bach to leave Tokyo, where there is a state of emergency, and come to Hiroshima is not something that will be accepted by a lot of people,” the Hiroshima Congress against A- and H-Bombs said in a statement. “It’s inevitable that his trip will be criticized as being taken for political reasons.”

Opponents also noted the timing of the visit. Friday was exactly 76 years after the Trinity nuclear test in New Mexico that directly preceded the attacks on Hiroshima and Nagasaki.

Kunihiko Sakuma, head of a group supporting hibakusha — survivors of the twin atomic bombings — told the Kyodo News agency that holding the Olympics when lives are being lost because of the pandemic “runs counter to the spirit of the Games that is supposed to be a 'festival of peace.’ ”

Nevertheless, some residents welcome any international support and attention for the cause of peace.

“The Olympics is an international event. I understand there is an Olympic truce a few days before the opening. I’m very happy about that,” 53-year-old day-care worker Chiemi Sugimoto told the Reuters news agency.

Ran Zwigenberg, a specialist in the history of Hiroshima at Penn State University, said the protests reflect Hiroshima’s deep aversion to having its suffering politicized and exploited by outsiders, with the monument having a meaningful status as a place of pilgrimage for peace. That aversion has been fueled by the opposition these Games have attracted in Japan, with most people wanting them canceled and many on the left seeing the IOC as a capitalist organization motivated by financial gain, he said.

“That connection between obviously being exposed as a moneymaking machine and their hypocrisy of professing peace, that’s something that has really rubbed people up the wrong way,” Zwigenberg said.

Bach also plans to visit Sapporo to watch the women’s marathon Aug. 7 as well as Fukushima, which is hosting seven baseball and softball games.

Japan won its bid to host the Olympics after pitching them as a symbol of Fukushima’s recovery from the 2011 earthquake, tsunami and nuclear meltdown, but most events set to take place in the prefecture during the Games and meant to show the region in a positive light were canceled after organizers banned spectators from venues last week.