Auckland police are investigating an allegation that has been made against four England players following an alleged incident in the team hotel.
The Rugby Football Union confirmed they are fully co-operating with police over the matter.
The alleged incident occurred in a private room at the team's Hilton hotel in the early hours of Sunday morning (local time) after England's 37-20 defeat to New Zealand.
In a brief statement, the RFU said: "The England rugby team has been informed by Auckland Police that an allegation has been made against four members of the England playing squad.
"Whilst no formal complaint has been made we are co-operating with the police and their enquiries.
"In the circumstances we are unable to make any further comment."
A spokesperson for Auckland police would not confirm the nature of the allegation nor confirm the identity of the players.
The Auckland police have released a statement confirming an investigation is under way.
It read: "Auckland City CIB is investigating an allegation involving up to four members of the England rugby team.
"The incident being investigated is alleged to have occurred early on Sunday, June 15, in a private room.
"Whilst an allegation was brought to the attention of police on Sunday evening, no formal complaint has been received.
"Investigating officers are receiving the appropriate level of co-operation from the England rugby team management."
England are in Christchurch preparing for the second Test against the All Blacks on Saturday.
Rob Andrew, the RFU elite rugby director, added: “The players concerned have the complete support of all the players and the management.”