The flame for this summer's Tokyo Olympics was lit Thursday in ancient Olympia, Greece, without spectators present as the global spread of the new coronavirus has cast doubt over whether the quadrennial sporting event will go ahead as scheduled.

The lighting ceremony, marking the start of a torch relay that will end with the opening ceremony on July 24 in the Japanese capital, was held in the presence of a limited number of delegations, officials and journalists, a day after the World Health Organization labeled the outbreak of the virus a "pandemic."

The virus that broke out in China late last year has since spread to more than 100 countries, with some health experts now saying that the impact on the games from the WHO's designation would inevitably be adverse.

(Anna Korakaki, right, passes the flame to Mizuki Noguchi.)

The virus has prompted organizers not only to scale down the traditional ceremony, allowing as few as 100 Olympic representatives to participate, but also many other festivities leading up to the Summer Games.

As concerns mount over Olympic preparations, Greek actress Xanthi Georgiou, dressed as a high priestess, ignited the flame using the sun's rays and a parabolic mirror at the Temple of Hera.

International Olympic Committee chief Thomas Bach said Olympic organizers are committed to the "success" of the games, despite "difficult circumstances."

"We're strengthened in this commitment by the many authorities and sports organizations around the world who are taking so many significant measures to contain the spread of the coronavirus," Bach said.

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The lighting ceremony came a day also after Japan marked the ninth anniversary of the catastrophic earthquake and tsunami in its northeastern region that left nearly 16,000 people dead and triggered a nuclear disaster in Fukushima.

Japanese officials hope to showcase the recovery of the region through the Olympics.

"The Olympic torch relay in Greece is the origin of so many wonderful episodes and stories, and I very much hope that the torch relay that begins today will engender many dreams and aspirations and bring hope for tomorrow," Toshiaki Endo, vice president of the Japanese organizing committee, said at the ceremony.

Greek Olympic shooting champion Anna Korakaki started the torch relay as the first woman to do so in the history of the games. She passed the flame to Japanese athlete Mizuki Noguchi, winner of the women's marathon at the 2004 Olympics in Athens.

Following the eight-day Greek leg of the relay, the flame will be handed over to Japan on March 19 at the Panathenaic Stadium in Athens, where the first modern Olympics were staged in 1896.

The handover ceremony will be smaller than originally planned, possibly without the presence of spectators, also due to fears over the virus that has killed nearly 4,300 people and infected some 118,000 others around the world.

The flame will arrive at the Japanese Air Self-Defense Force's Matsushima base in Miyagi Prefecture aboard a chartered plane, accompanied by Japanese judoka Tadahiro Nomura and wrestler Saori Yoshida, both three-time Olympic gold medalists, who will be among the torchbearers on the final day of the Greek leg of the relay.

The flame will be put on public display in areas hit hard by the 2011 triple disaster before the 121-day Japanese torch relay kicks off on March 26 at the J-Village soccer training center in Fukushima Prefecture, which served as an emergency response headquarters during the nuclear disaster.

The 71-centimeter torch, bearing the motif of Japan's iconic "sakura" cherry blossoms, will then journey through each of the remaining 46 prefectures in the country as it leads into Tokyo, which will host the Summer Games for the second time, the first being in 1964.