Super League and the Rugby Football League have suspended the season until 3 April as a result of the spread of coronavirus.
Most games went ahead as planned at the weekend, with the RFL saying on Friday that it would be "following the government's guidance as requested".
However, a change to government advice, warning against mass gatherings, has prompted the postponement.
It applies to all tiers, including the men's, women's and community game.
"These are unprecedented times, and they present significant financial and commercial implications for rugby league, which will be further considered during the period of suspension," said the joint statement from Robert Elstone, the executive chairman of Super League Europe, and Ralph Rimmer, CEO of RFL.
"Super League is also an international competition, and consideration has to be given to our clubs in Canada and France, particularly around travel restrictions and scheduling fixtures.
"Player welfare and maintaining the integrity of the competition are key concerns moving forward. Equally our responsibilities to rugby league communities remain front of mind for all of us.
"The whole country is facing major challenges - and the support of our fans, partners and stakeholders is needed now more than ever before."
One of the points in Prime Minister Boris Johnson's briefing on Monday was the decision to withdraw the support of emergency workers at mass gatherings, such as sporting events.
There is a mandatory requirement to have a doctor and physiotherapist at Super League games. while best practice advice is to have secondary doctor and physiotherapist cover at every match.
While there are currently no confirmed cases of coronavirus within rugby league, Toronto Wolfpack said they have four players under self-isolation after reporting symptoms, and have stood down their playing staff accordingly.
Earlier on Monday, St Helens chairman Eamonn McManus said the "very existence of the sport" was in danger if the government did not offer financial support to clubs during any postponement to the season.
"The government has to look at a degree of support for our sport. There's huge financial implications - the very existence of our sport is on the line," he told BBC Radio 4's Today programme.
"We're different to soccer, probably different to rugby union. We're at the beginning of our season. This is open-ended both in time and terms of quantum. No-one knows the full extent of it."