Detectives are investigating a "serious allegation" made against the players by the alleged victim's boyfriend, it was claimed.

Two players are reported to have had sex with an 18-year-old girl in a hotel room in Auckland where the team are on tour. Two other unnamed players watched the girl perform sex acts, it was claimed.

Team bosses said players would co-operate with police but said no official complaint had been made.

The alleged incident occurred in a room at the Hilton Hotel in the early hours of Sunday following England's 37-20 defeat to the All Blacks. Players engaged in a "rowdy" drinking session in a bar called The Pony Club before returning to the hotel with up to six women, according to reports.

A source told The Sun the woman had sex willingly with one player and did not object when a second joined in.

An Auckland police spokeswoman said: "We have made it known to the England management via their representatives that we would like to speak with the team members. There are no arrangements to do so."

Director of rugby Rob Andrew said England were fully co-operating with police in the matter and that the four players had the "complete support" of the team and management.

He 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 inquiries.

"The players concerned have the complete support of all the players and the management. In the circumstances, we are unable to make any further comment."