Four England players have denied an allegation of "serious sexual assault" and declined to be interviewed by New Zealand police over the matter.

The Auckland police's adult sexual assaults team are investigating an allegation of rape and/or sexual assault, said to have occurred early on Sunday morning in a private room at the Auckland Hilton hotel after England's 37-20 defeat to New Zealand.

No formal complaint has been made by the woman allegedly involved.

The specialist team of officers from Auckland's Criminal Investigation Bureau flew to Christchurch — where the team are currently based ahead of tomorrow's second Test — in the hope of speaking with the players at the centre of the allegation.

But England confirmed the players declined to speak with the authorities, after taking independent legal advice.

An RFU statement confirmed: "The England rugby squad can confirm that a request was made by the Auckland Police for certain playing members of the squad to voluntarily attend a meeting with Christchurch Police in order to speak to officers concerning the allegations presently under investigation.

"Those players have each received legal advice from lawyers engaged to independently consider their interests. In the absence of any formal complaint in this matter the players were advised to decline the request made to them to voluntarily attend upon the police and it is fully within their rights to do so.

"The players continue to deny the allegations and have the full support of the England management, coaches and players."

The Auckland police have confirmed the nature of the "serious sexual assault allegation" for the first time.