Baron says the quartet are "angry" they cannot clear their names
England players will be banned from bringing women back to their hotel rooms on future tours abroad under a new code of conduct.
The Rugby Football Union has agreed a new set of standards after four members of the England squad were accused of a serious sexual assault in New Zealand.
The four players have denied the allegation in the "strongest terms".
The new code of conduct will come into force from 1 July when players will sign their new elite rugby contracts.
The move by the RFU follows a tumultuous week for English rugby, which has seen Auckland police's adult sexual assault team investigating an incident alleged to have occurred at the England hotel early last Sunday morning.
The alleged incident was said to have occurred in a private room at the Hilton Hotel hours after the 37-20 defeat by the All Blacks.
The four players have not been identified and have declined to be interviewed by New Zealand police at this stage as the woman in question has not made a formal complaint.
The players have and will continue to have our full support in their efforts to clear their names as soon as possible
RFU chief executive Francis Baron
England tour manager Rob Andrew has insisted that the players concerned "have the complete support of all the players and the management".
RFU chief executive Francis Baron confirmed the issue of women being entertained by players in their hotel rooms would be addressed.
"The code of conduct has never specifically dealt with that aspect," he said.
"Talking with my colleagues in the New Zealand Rugby Union, for example, who have had incidents like this in the past, they have moved to a much more prescriptive code of conduct about women being allowed into the team hotel.
"This is the first time the England rugby team has got into this position. It is distressing to everybody involved.
"In a way it makes us absolutely determined to do whatever we can to ensure such a set of circumstances never happens again."
The four players have declined to be questioned by police after taking legal advice, and Baron says they are "very upset and very frustrated" that they cannot actively clear their names.
"Each of the individuals has denied any wrong-doing in the strongest terms," he added. "There are some lurid allegations floating around. In our view those boys are innocent until proven otherwise.
"The players have and will continue to have our full support in their efforts to clear their names as soon as possible.
"It is a very difficult situation with no complaint being made. You are trying to clear yourself but against what?
"I hope I am conveying the anger and frustration those young men are currently facing. There doesn't appear to be any immediate end to the process, in the absence of there being a complaint."
Security guards have been posted in the England team hotel in Christchurch, where they are preparing for Saturday's second Test against the All Blacks.
The squad are set to leave New Zealand for home on Sunday and they will be free to do so unless there is a change in the situation.