While the public voice has never been stronger in his favour, South Sydney winger Alex Johnston is set to be denied a World Cup berth with the Kangaroos due to International Rugby League's eligibility rules.

Johnston made his debut for Australia in the 2015 ANZAC Test against New Zealand, though the prolific try-scorer has never handed a green and gold jersey since that day.

The Rabbitohs junior is finally being recognised for his stunning try-scoring record by the public, notching 58 tries since Round 1, 2021, and moving well in reach of Ken Irvine's 212 career tries, despite being just 27 years-old.

The public aren't the only ones in Johnston's corner for a Kangaroo call up, South Sydney team mate believes the 'best finisher ever' should join him in England for the tournament.

"I'd put him in the Australian side, to be honest. He deserves it," Mitchell told AAP a fortnight ago.

NRL Rd 3 - Rabbitohs v Roosters
SYDNEY, AUSTRALIA - MARCH 25: Latrell Mitchell of the Rabbitohs celebrates with Alex Johnston of the Rabbitohs after scoring a try during the round three NRL match between the South Sydney Rabbitohs and the Sydney Roosters at Accor Stadium, on March 25, 2022, in Sydney, Australia. (Photo by Matt King/Getty Images)

While the drums have been beating louder and louder for Johnston to earn a place in Mal Meninga's World Cup squad, the IRL's eligibility rules are set to deny the speedster from donning the green and gold this year.

Johnston has become a mainstay in the Papua New Guinea Kumuls side, lining up at fullback for their midseason test victory over Fiji, playing all three of his career PNG games in the custodian role.

However, when the IRL updated a host of their eligibility rules at the beginning of 2020, they ruled that 'a player can only elect one nation to represent in any calendar year'.

Rule viii explicitly states the following:

"A player who has elected to represent a Nation cannot then elect to represent another Nation in the same calendar year."

While players can change freely between Tier 1 and Tier 2 nations having not played already that year, rule x continues to elaborate that the ability to switch is only in accordance with the previous rule as follows:

"Pursuant to Rule (viii), a player is entitled to move between a Tier One and a Tier Two or Tier Three Nation freely save that a Player may not change their National Team during any IRL Global Event (including any qualification matches played as part of that IRL Global Event, including Continental Qualification Matches) in which that Player is participating and may only represent one Nation during each IRL Global Event."

While the rules mean Johnston could switch back to the Kangaroos in 2023 due to PNG not being a Tier 1 nation, his mid-year appearance for the Kumuls leaves the flyer ineligible to run out for Australia at this year's World Cup.

It's expected Johnston will still participate in this year's Rugby League World Cup, however he'll be donning the PNG jersey instead of Australia.

He won't be the only South Sydney star playing for a lower-tier nation, with Lachlan Ilias and Peter Mamouzelos set to be selected for Greece, Tevita Tatola and Keaon Koloamatangi for Tonga, Davvy Moale for the Cook Islands while Campbell Graham is set to run out for Scotland during the six week tournament.