The International Judo Federation (IJF) has announced the Rabat Grand Prix, due to begin on Friday (March 6), has been cancelled.
The decision comes as a result of new Government measures aimed at stopping the spread of coronavirus.
It was "cancelled upon decision of the Moroccan Government" according to an IJF statement.
"All international sports competitions, exhibitions and public gatherings have also been cancelled or postponed in the country.
"We apologize for the unexpected occurrence of the event and we do understand the inconvenience for all stakeholders, especially for our athletes and delegations.
"The IJF is currently searching for the appropriate solutions for this unexpected situation and all its consequences across all levels."
It was expected that Frenchman Teddy Riner would return to action for the first time since suffering a shock loss at the Paris Grand Slam last month.
That defeat was his first in almost a decade.
Registration for the Ekaterinburg Grand Slam - which is set to start on March 13 - has been reopened as "a first emergency measure", the IJF said as a result of the cancellation.
Morocco confirmed its first case of the virus - named COVID-19 by the World Health organization - yesterday, with the patient someone who had been living in Italy.
There have been more than 92,000 confirmed cases across the globe, with China, South Korea, Iran and Italy hardest hit.
The outbreak is disrupting many sports' preparations for Tokyo 2020, with qualifying events among those postponed or cancelled.
Chinese judoka were unable to take part in the Paris Grand Slam because the French embassy in China was shut as a result of the outbreak.
IJF President Marius Vizer has previously said the IJF will attempt to secure an increase in quota places to ensure athletes having difficulty competing in pre-Olympic events don't miss out on a place at Tokyo 2020 as a result of the coronavirus crisis.