Optional law amendments limiting contact in scrums, the number of players in a maul, and the duration of rucks have been approved by World Rugby in the hope of reducing the risk of possible transmission of COVID-19 during the pandemic.

Rugby's governing body made the announcement on Thursday, leaving national unions to decide whether to adopt the amendments at elite or community level depending on the prevalence of the virus in their territory and the advice from government and public health authorities.

A package of best-practice hygiene measures, such as regular ball sanitization and the "prevention of spitting and nose clearance" during matches, was also announced in an effort to reduce exposure.

"We have extensively evaluated the perceived risk areas within the game in partnership with our unions," said World Rugby chairman Bill Beaumont, adding the temporary measures will "aid safe return to rugby activities at all levels."

The scrum is a key tenet of the game -- it was a major factor in South Africa winning the World Cup last year and has long been part of the rugby DNA of national teams such as England and Argentina -- but there is potential for its effectiveness to be stymied if a union adopts the amendments.

Scrum re-sets, which happen an average 3.5 times per game according to World Rugby, are being removed when no infringement occurs. Instead, there would be a free kick to the team which put the ball into the original scrum.

There will be no scrum option for a penalty or free kick, and there will be a goal-line dropout when an attacker is held up in-goal.

As for mauls, no player is allowed to join one if not in it at the start, and only one forward movement is allowed.

At rucks, referees will ask players to release the ball after three seconds instead of the current five.

World Rugby is also pushing to remove choke tackles and for players to tackle opponents lower because of the reduced transmission rate compared to upright tackling. Sin-bins will increase by five minutes to 15.

In New Zealand, which has limited the number of confirmed cases of COVID-19 to 1,154 and known deaths to 21, a domestic Super Rugby tournament is set to begin on June 13, marking the first major club competition since the suspension of rugby union in March. Organizers say it will be played under traditional laws.

"There don't appear to be any signs of community transmission in New Zealand so ... we don't anticipate the need to adopt the law proposals," New Zealand Rugby chief executive Mark Robinson said. "We have been open with World Rugby about this and they understand our unique situation."

The situation is likely to be different in parts of Europe and North America, where countries are only starting to ease lockdown restrictions. Rugby is unlikely to return in Ireland for several months, for example, while the English top division has yet to announce when it will be resuming.

In response to the World Rugby announcement, England's Rugby Football Union said it has its "own review underway looking at the options for return-to-training and return-to-play rugby for clubs."

"When government advice on social distancing measures are lifted," the body said, "specific RFU guidance will be announced and provided to clubs."

Speaking before the amendments were announced, Barry O'Driscoll, a former medical advisor to the world governing body, told The Associated Press that making changes to the scrum and mauls was "eroding a big part of what rugby is all about."

"The set scrum, if one side gets on top, can win games for a team," O'Driscoll, an ex-Ireland international, said. "Psychologically, it's very stressful and damaging for the opposing side."

Rugby, in general, has "huge" issues compared with, for example, soccer, O'Driscoll said, simply because the ball touches players' hands so often and that's a way COVID-19 is transmitted.

Pat Parfrey, a World Rugby council member who is a leading official for Rugby Canada, told the AP he couldn't contemplate the game at international level going ahead without its usual scrums, rucks and mauls.

"The game is all about continuity," he said, "so I think that would be a totally different game."

Parfrey, who is also a leading clinical epidemiologist in Canada, said an activity like tag rugby -- a non-contact version of the sport where a tackle is made by pulling a tag off the belt of the opponent who has the ball -- could "initiate the club game" at amateur level.