Sumo's spring tournament began behind closed doors on Sunday, the latest big event in Japan to be hit by the coronavirus less than five months before the Tokyo Olympics.

The Japan Sumo Association said in the previous week spectators would be barred the tournament in Osaka from Sunday until March 22, as the virus has infected at least 454 people across Japan and been linked to seven deaths.

On Sunday, public broadcaster NHK carried two hours of live programing from the tournament.

"This tournament without spectators would be an extremely hard one for sumo wrestlers as they struggle to focus their minds," Sumo Association chairman Hakkaku said in his welcoming address.

Viewers could hear sounds usually drowned out by spectators, including that of the wresters slapping their bellies and wiping their feet in the ring.

Some sumo rituals were also amended, including the traditional ladle of water that a winning wrestler offers to the next in the ring.

Sumo stars have already been taking precautions at fan events, refraining from shaking hands and wearing surgical masks, while a ceremonial visit to a local shrine was cancelled.

The viral outbreak across Japan and dozens of other countries has fuelled concerns about the Summer Olympics, which open on July 24.

IOC President Thomas Bach, however, insisted that the nightmare scenario of either cancelling or postponing the Tokyo Olympics was not discussed at a recent key meeting.