A sumo stablemaster and five wrestlers have contracted the coronavirus, the Japan Sumo Association said Saturday, casting doubt on whether next month's Summer Grand Sumo Tournament in Tokyo can go ahead as scheduled.

According to the JSA, stablemaster Takadagawa has contracted the virus along with Hakuyozan, a wrestler at his stable in Tokyo who competes in the second-tier juryo division.

Four wrestlers who belong to the lower divisions have also contracted the virus. The JSA did not disclose their names and stables citing privacy reasons.

Earlier this month, a wrestler competing in one of the lower divisions tested positive for the virus, marking the first confirmed case in the country's ancient sport.

The JSA delayed the start of the 15-day Summer tournament in Tokyo by two weeks in response to the pandemic, with the opening day now slated for May 24. But it has said the meet might be held without spectators or canceled altogether depending on the situation.

March's spring tournament in Osaka was held behind closed doors in a bid to slow the spread of the virus.