The 2021 Rugby League World Cup is in jeopardy after Australia and New Zealand pulled out of the tournament due to player welfare concerns amid rising coronavirus cases.
The two heavyweight nations of the game have cited a spike in COVID-19 infections in the UK and a "worsening environment" in Australia.
England and Samoa are due to kick off the tournament at St James' Park on October 23.
The Australian Rugby League Commission (ARLC) and New Zealand Rugby League (NZRL) have requested that the tournament be moved to 2022, although this is a course of action organisers may be loath to take given the prospects of a clash with the 2022 Cricket World Cup in Australia and the 2022 FIFA World Cup in Qatar.
"The decision to withdraw from the RLWC2021 comes after considering the risk of COVID-19 infection in the United Kingdom, the worsening environment in Australia and the time a majority of NRL Premiership players will spend away from home under strict biosecurity conditions prior to the World Cup," a joint statement read.
"The ARLC and NZRL have resolved, that in the present environment the risks to athletes and officials travelling to the UK to participate in the tournament this year are too great, and it is unable to endorse Australia and New Zealand participating in the RLWC in 2021."
The withdrawal comes despite the fact Australia's rugby union team are still slated to play England at Twickenham on November 13.
Tournament organisers issued a statement expressing frustration at the announcement.
"RLWC2021 note the disappointing statement made by the ARLC and NZRL which may have wide ranging implications for international rugby league," read the Rugby League World Cup statement. "RLWC2021 were informed at very short notice and will continue discussions with all stakeholders to agree on the best way forward."
ARLC chairman Peter V'landys said: "Not participating in this year's World Cup is not a decision the commission has taken lightly, but we must put the best interests of our players and officials first. Protecting them is our absolute priority.
"In the current environment, the risks to the safety, health and wellbeing of the players and officials travelling from Australia to participate in the tournament this year are insurmountable.
"The majority of NRL players are currently living away from home under difficult biosecurity protocols. They would then be required to remain under protocols and away from home for the duration of the tournament before again quarantining on return to Australia. This is too much to ask our players and officials to do."
NZRL CEO Greg Peters added: "The safety and wellbeing of our people is the main priority, and unfortunately, that cannot be guaranteed to our satisfaction.
"There are stark differences between how the pandemic is being managed in the UK compared to Australasia and recent developments have highlighted how quickly things can change.
"The tournament organisers have moved heaven and earth to make this work, so it is not an easy decision, but the COVID-19 situation in the UK shows no sign of improving, and it's simply too unsafe to send teams and staff over."
Australia have won 11 of the 15 editions of the Rugby League World Cup, while New Zealand's 2008 triumph means there has not been a winner from outside Australasia since Great Britain in 1972.