A woman who spent the night with an English rugby player at the Hilton Hotel in Auckland has revealed how four other players entered the room and one stripped the duvet off their semi-naked bodies.

The woman says she was one of several who met the players and later accompanied them to their hotel.

Police have confirmed they are investigating a separate "serious allegation" involving up to four team members at the five-star hotel early last Sunday.

No formal complaint had been received by the police, who would not identify the person who made the allegation, a police spokeswoman said. England rugby coach Rob Andrew has backed his players and says the team is cooperating with the investigation.

The woman, who is not the person at the centre of the allegation to police, said she spent the night at the hotel with an English player.

She told of another incident involving players several hours after the matter that police are investigating.

The 22-year-old woman, who wanted to be known only as Angel, revealed the team was drinking at an Auckland bar after Saturday night's loss to the All Blacks.

She said she "hit it off" with the players after meeting them at the Pony Club bar in the central city.

She continued drinking with them at the bar till the early hours and then went back to the Hilton Hotel at the Viaduct Basin with one player.

She understood about five other girls went back to the hotel with team members.

Police say the allegation relates to early on Sunday morning.

Angel said the players got up about 9am on Sunday for a swim and physiotherapy and then returned to their rooms.

"After that ... I was in the room with the guy I was with and there was a knock at the door and there was about four of them at the door," she said.

"They were pretty persistent so [we] eventually let them in."

"We were chatting for a while then all of a sudden one of the players pulled the duvet off them. He was almost nervous to do it," Angel said. "I was sort of semi-dressed so it wasn't too bad."

The players then ran out of the room with the duvet and down the hallway, where they were "told off by a maid".

The player she was with apologised for their behaviour, saying it was "just the young ones", Angel said.

She believed other women who went back to the hotel with players also had their duvets pulled from them. "They were doing the rounds.

"I almost felt a little unsafe ...a bit defensive about it. What can you expect when you let four guys into your room?"

Police spokeswoman Noreen Hegarty said police had not sought to speak to the England players directly but had been liaising with the squad's management.

Andrew said the team was cooperating with police. "We completely support our players," he said.

Ms Hegarty said that unless someone was able to corroborate the allegation, it could "end up going nowhere".

The England team is due to leave New Zealand on Sunday.