In a letter seen by the BBC, Fina also criticises the Japanese government which, in its opinion, “did not take all the necessary measures to ensure successful and fair” competition.
The event was scheduled to run from 18-23 April, and was due to be the final Olympic qualifier and an official test event for the postponed Tokyo Games.
“Fina sincerely regrets this situation,” read the letter. “Despite all best efforts and understanding from Fina, the Executive was obliged to take this drastic decision.”
Fina informed national federations by email on Thursday after receiving what it describes as “worrying” information about the organiser’s proposed Covid-19 strategy, through its taskforce.
“In their view, this plan will not properly ensure health and protection guarantees to participants,” continued the letter.