Officials have said that a coronavirus cluster has been detected at a Japanese hotel where dozens of Brazilian Olympic team members are staying, raising concerns of Covid-19 infections spreading between locals and Olympic staff and athletes, Reuters reports.

Seven staff at the hotel in the city of Hamamatsu, southwest of Tokyo, have tested positive, said a city official, but the 31 members of the Brazilian Olympic delegation, which includes judo athletes, are in a "bubble" inside the hotel separated from other guests and have not been infected.

The cases were found during a routine screening process required before the staff started work, said city official Yoshinobu Sawada, adding the unidentified hotel was now considered a Covid-19 cluster.