State authorities on Wednesday warned Australia's National Rugby League (NRL) that next month's restarted season could end immediately if players continue to flout coronavirus lockdown rules.

The NRL late on Tuesday announced fresh details of the ambitious programme to resume competition from 28 May, but they were overshadowed by the news of four players being fined for lockdown breaches.

With players hoping to begin training on Monday, New South Wales Deputy Premier John Barilaro said the NRL was on notice.

"This is the warning shot," Barilaro told Sydney's Daily Telegraph. "When the game gets going again, no player can breach the rules.

"Once the NRL competition is up and running, players must understand their actions could have broader ramifications for the entire game."

Barilaro has been an outspoken supporter of restarting the season but expressed frustration at the actions of South Sydney's Latrell Mitchell, Melbourne's Josh Addo-Carr, Newcastle's Tyronne Roberts-Davis and Nathan Cleary of Penrith.

"People are working tirelessly to get rugby league going again and these players jeopardise that," he said.

Mitchell, Addo-Carr and Roberts-Davis went on a camping trip over the weekend, while Cleary was photographed breaching social distancing rules in a room full of women.

All received fines ranging from Aus$10 000 to Aus$50 000, with 60 percent suspended, and will be sidelined for at least one match if they reoffend.

Police have also fined Mitchell and Addo-Carr Aus$1 000 each and charged the pair with firearms offences linked to the weekend trip.

The NRL season was suspended on 24 March after just two rounds amid a government shutdown of all non-essential gatherings in a bid to stem the spread of coronavirus.

Under plans thrashed out by the NRL and its broadcast partners this week, the season will be cut from 25 rounds to 20 - including the two already played - with a four-week playoff series ending in a Grand Final on 25 October.

The three-match State of Origin series between NSW and Queensland, normally played mid-season, will shift to November for the first time.

Reports said all matches would be played in Sydney, although discussions were underway with state governments to let the three Queensland-based clubs and Melbourne Storm train at home.

Australian border authorities said the NRL had applied for an exemption to allow the Auckland-based New Zealand Warriors to enter Australia but no decision had been made.

If the application is approved, the Warriors plan to be based in rural Tamworth, although it is understood they are still waiting to find out what extra remuneration they would receive for spending up to six months away from their families.