A rugby union player has died after suffering a head injury during a game in mid-northern New South Wales.

Quirindi Lions player Nicholas Tooth, 25, collapsed after a tackle during a Central North first grade clash against the Narrabri Blue Boars on Saturday.

First aid was administered at Quirindi Rugby Park before he was airlifted to Newcastle's John Hunter Hospital in a critical condition.

Police said Mr Tooth suffered an apparent head injury and he died in hospital on Sunday afternoon.

Mr Tooth studied agricultural economics at the University of Sydney and went to Sydney Church of England Grammar School (Shore) in North Sydney.

He was originally from Wallabadah in the New England region of NSW but had been living in Sydney.

Police said the incident was not being treated as suspicious, but a report was being prepared for the coroner.

President of the Quirindi Lions football club, Charles Murray, told ABC New England that Mr Tooth was visiting his home town from Sydney for the weekend.

'It was just a very tragic accident'

He said Mr Tooth decided to compete with the first grade squad and added there was "nothing untoward" in the tackle that injured Mr Tooth.

"It really was just a tragic accident, Nick went in to tackle an opponent and his head clashed with [the opponent's] shoulder and he went down," Mr Murray said.

"There was no foul play, nothing untoward about it at all, sadly it was just a very tragic accident."

Mr Murray said Mr Tooth had been working his way up in the agricultural grain industry.

"I'd seen him grow up from a child through junior rugby and grow into a young man, he was a lovely kid, he had a bit of a larrikin spirit in him," he said.

"He was a really good bloke and very popular, and his family for generations have been great rugby supporters in this district and great community people."

Mr Murray said Australian Rugby Union was offering assistance to the club and counsellors would be made available to affected players.

"It's imperative that we keep them together and we keep them talking about it, and they get it out in the open rather than bottle it up," he said.

In a statement, Australian Rugby Union chief executive Bill Pulver thanked those who helped at the scene and confirmed support would be offered to Mr Tooth's family and club.

"The passing of one of our young country rugby players over the weekend is incredibly sad and is a loss that is felt by the entire Australian rugby community," he said.

Tributes flow on social media

Central North Rugby Union president Tony Byrne has expressed his shock and sadness following Mr Tooth's death.

Mr Byrnes said his thoughts were with the Tooth family, the Quirindi Rugby Club and the Quirindi community.

He said the local rugby fraternity was in shock and that the association would offer support to the rugby community, including Mr Tooth's family.

On social media, friends have described the rugby player as "the best bloke".

"I am really going to miss him and his good nature - he is one of the best blokes I know," Charlie Begg said on Facebook.

Les Witts said Mr Tooth was "a tru [sic] character, a little legend you are".

The Quirindi Lions Rugby Club's Facebook said in a post "the loss of this kind hearted and fine young man will be felt far and wide".