It came after South Canterbury scored a try with five minutes left in the match to put Whanganui out of reach of the Meads Cup at the Temuka Domain.
Around 50 fans, including South Canterbury’s mascot, invaded the pitch in celebration of their team’s try, but it soon turned ugly.
The fans began pulling in Whanganui players to their celebratory huddle, prompting some pushing and shoving.
One Whanganui player can be seen being mobbed by their opposition’s fans.
The New Zealand Herald understands punches were allegedly thrown by South Canterbury fans.
Whanganui Rugby chief executive Bridget Belsham said she was not in a position to comment on what happened during the Meads Cup final.
The New Zealand Herald has approached New Zealand Rugby for comment.
The incident marred South Canterbury’s win of the Heartland Championship - for the third time in a row.
They beat Whanganui 40-30 in Temuka to lift the Meads Cup yet again.
South Canterbury won an amazing 31 straight games.
