A Tokyo Olympics water polo test event has been postponed, organisers said Tuesday, following reports it had been called off because sport officials cannot enter Japan due to virus restrictions.

Test events function as dress rehearsals for each sport, and the two-day water polo test was supposed to open on Saturday but will now be held in May or June, Tokyo 2020 organisers said.

A series of qualifiers and tests for the virus-delayed Tokyo Games -- due to open on July 23 -- have been cancelled or postponed because of Covid-19 border rules.

Tokyo 2020 said in consultation with others, including the International Swimming Federation (FINA), a decision had been taken to postpone the event.

"In order to ensure the best level of preparations for these test events and for the Tokyo 2020 Games, considering the schedule of each stakeholder under the current global Covid-19 conditions, it was felt that postponing the events was necessary," Tokyo 2020 said.

Local media earlier reported that the event had been cancelled because of Japan's strict travel regulations -- which bar virtually all foreign nationals from entering the country.

The reports said time-keepers and record-keepers who were due to travel to Japan could not take part in the event.

Test events for the Games resumed last weekend for the first time since the pandemic began, with a wheelchair rugby event held at Tokyo's Yoyogi National Stadium.

Virus measures have forced the postponement or cancellation of a string of Olympic qualifiers and test events
Virus measures have forced the postponement or cancellation of a string of Olympic qualifiers and test events AFP / Philip FONG

But there are doubts over whether the remaining 17 test events can be held as scheduled.

Last week, FINA said it was considering moving its Olympic qualifiers from Japan.

Those events include the Diving World Cup scheduled for this month and the Artistic Swimming qualifier scheduled for May.

FINA's competition calendar already lists both events, along with the May 29-30 Olympic marathon swim qualifier in Japan's Fukuoka, as cancelled.

But the two events were still listed on an updated test event calendar provided by Tokyo 2020 on Tuesday.

FINA reportedly told member nations last week that it had received "worrying" information about the organiser's proposed virus countermeasures.

On Monday, the Japan Triathlon Union also announced that a triathlon World Cup event due to be held in Osaka in May has been cancelled because of virus restrictions.

The competition was not an Olympic test event but helps decide which athletes will qualify for the Games, and was meant to feature 130 triathletes from 30 different countries.