Senior executives at three of Japan’s Olympic sponsors have said privately the Tokyo Games will probably be postponed because of coronavirus, despite reassurances from the event’s organisers that plans have not changed.

Pessimism over the July 24 start date has deepened since the weekend, according to one executive, as the coronavirus outbreak has accelerated in Europe and the US. Japan has already closed schools, banned visitors from certain countries and mandated that some sports fixtures be contested in front of empty stands.

The three sponsors, whose executives spoke on condition of anonymity and include two of the 15 “gold” partners — the top-paying domestic sponsors — of the Games, have collectively spent more than $200m to support an event that has cost more than $12bn to prepare. The Games rank as the most sponsored event in sports history.