A Super Rugby franchise based in New Zealand's Waikato region has long used the Chiefs name, prompting objections to the NRL's choice of branding for its incoming team.
New Zealand Rugby has now begun legal proceedings against the NRL over the name, which could force the Australian government-backed PNG Chiefs to rebrand.
The NRL's 19th team is due to enter the competition as the PNG Chiefs.
Last month, the outlet reported that New Zealand Rugby had warned the NRL it would take legal action unless it reconsidered the name.
Proceedings began after Australian Rugby League Commission executive chairman Peter V'landys said the NRL had no intention of changing it.