Tim Nanai-Williams believes Samoa could compete on an equal footing if rugby union’s authorities follow their league counterparts and introduce legislation that would allow his cousin Sonny Bill Williams potentially to play alongside him for the Pacific island side in the future.

Last year rugby league’s eligibility rules were changed to free up players with dual nationality who were not picked by tier-one nations – Australia, New Zealand and England – to represent tier-two sides at the World Cup, now at the semi-final stage.

The move has polarised opinion after Jason Taumalolo’s high-profile defection from New Zealand to Tonga last month but it has resulted in a considerably more competitive tournament. Taumalolo’s Tonga beat New Zealand in the group stages while Fiji – beneficiaries of the law change with Jarryd Hayne in their ranks – have also reached the last four after beating the Kiwis in the quarter-finals.

“I would love to see it happen,” said Nanai-Williams, who has been named at fly-half in the Samoa side to face England on Saturday. “It is great in my eyes to see league doing that. The [Rugby League] World Cup is a real level playing field. Everyone before was saying that it would be Australia and New Zealand in the final and now you have Fiji and Tonga in the semi-finals. If that was to happen in rugby [union] that would be unreal and would make the game a lot better. It would grow it.”

With the Samoa union in financial turmoil – its chairman this month declared the organisation bankrupt – they languish 16th in the world rankings after the defeat by Romania last weekend. Player drain from the Pacific Islands is a significant factor – Bundee Aki, a close friend of Nanai-Williams, is the latest player of Samoan heritage to make his international debut for a tier-one nation, turning out for Ireland against South Africa this autumn, having qualified on residency.

World Rugby voted in May to extend the period of residency required to represent a new country from three to five years, a ruling which comes into force next year, but Nanai-Williams believes allowing players such as Sonny Bill Williams or Manu Tuilagi to represent Samoa when no longer on the radar for New Zealand or England would make a significant difference. Charles Piutau becomes the world’s highest-paid player when he moves to Bristol next season but the All Blacks’ selection policy means Steve Hansen will not consider him, and his New Zealand caps prevent him from representing Tonga.

“You can only imagine what it would do for world rugby and for Samoa if that ever happened with guys changing their allegiances,” said Nanai-Williams, who played for the Chiefs against the British & Irish Lions in June. “You see some of the stuff on social media with those Samoan XVs, guys from Samoa who have never played for Samoa, and a Tongan XV. It is quite scary when you see all the Pacific Island boys who have played for other countries.”

Changes to World Rugby’s eligibility regulations is an arduous and lengthy process and they state that any player to have played for a nation’s Test XV side, the “next” XV side (for example, England Saxons) or the sevens side, cannot represent another union. Nanai-Williams has experienced first hand the difficulty in navigating World Rugby’s red-tape having previously played for the New Zealand sevens team. The Auckland‑born 28-year-old became the first player to exploit a loophole whereby playing in a series of sevens tournaments for Samoa led to his eligibility for the XVs side.

“When you are young playing in New Zealand it is always the black jersey and also the [Samoa] jersey,” he said. “Both my parents are from Samoa and I speak fluent Samoan. I never thought of going overseas. There are guys who have come across to Europe as a personal thing. It is a good choice. It is a choice for their own individual. For me it is more like my loyalty to my roots. Some guys do get offers from clubs overseas and end up playing for England. I have no problem with guys going overseas to financially set themselves up and play for other countries.”

While Nanai-Williams is content playing in Super Rugby for the Chiefs, he acknowledges Saturday’s match against England at Twickenham serves as a shop window for some of his team-mates. “First we want to play our own game,” he said. “Samoa like to throw the ball around and there may be a few individuals who want to catch the eye of some other clubs.

“It’s a business. You want to perform well and be financially stable. There’s a team goal and an individual goal, too. We’ve got one kid [Melani Matavao] from the islands and another who doesn’t have a club. God willing, those guys get offers. We want to promote those boys.”