The players have refused to speak to detectives after taking legal advice.

They have vigorously denied the allegations.

Auckland Police confirmed the four are free to leave the country even though authorities are investigating claims of sexual assault or rape, reportedly on an 18-year-old woman at a hotel in the city last weekend after a tour match.

Reports claim two of the men had sex with the woman while two others watched.

One of the men accused of watching the alleged assault had sex with a blonde model on the same night, a newspaper reported.

A police spokeswoman said the victim had made the allegations to police herself, but had not yet made a formal complaint. She said the sportsmen could not be prevented from leaving the country on Sunday with the rest of the England squad in the absence of a formal complaint.

"At this stage it remains an allegation. If that changes then police could ask again to talk to the people involved," she said, adding police could seek to have the men extradited to New Zealand if a case was established against them. "Police could (extradite them), but whether they would do it I can't say. At this stage there is no reason to."

In response to the scandal, England rugby bosses on Friday announced a new set of standards for the players - including a clause preventing them bringing women back to the team hotel.

The rules will come into force when the players sign new contracts on July 1.