He turned down the Kiwis in 2018 to align with Queensland, but could yet represent New Zealand one day.
"Obviously, that (playing for the All Blacks) would be a huge goal, if I was to come back to union I'd want to tick," Ponga told TVNZ in 2018.
"I'm not too sure what my future holds — whether I'm going to stay in league or change codes but if I was to go back to rugby union I'd probably want to strive for that black jumper...it's the pinnacle."
Ponga has played 42 games for the club since his 2018 debut following a move from the Cowboys. The NRL season re-starts on Thursday, following the break for Covid-19, with the Broncos facing the Eels.
Newcastle look to make it three from three to start the season when they face the Panthers on Sunday. According to the SMH, Ponga could have signed his new deal before the season kicks off again.
"We've offered him an upgraded contract for 2020-21 on the basis of an extension," Knights chief executive Philip Gardner told the SMH in February.
"The family know how much we want to keep him at Newcastle and they will come back to us with their view.
"I'd be really surprised if the All Blacks weren't talking to him now, that's the kind of talent we are talking about here," Gardner said.
"He could play for the All Blacks, the Wallabies, or he may end up going to Japan or Europe. We genuinely want the best for the young man and while ever he wants to play rugby league, we want him to play here at Newcastle in an environment he enjoys.
"We have obviously put a deal forward that we believe is in the best interest of the club, but also in the best interest of him."