The BBC must be "firmer on excesses" in the wake of the Radio 2 offensive phone call row, BBC Trust chairman Sir Michael Lyons has said.
The calls made by Russell Brand and Jonathan Ross to actor Andrew Sachs "demonstrated the need for stricter controls", he said.
But, he added, the BBC must "be careful we do not retrench to a position where we're no longer willing to take risks".
Brand has resigned, while Ross has been suspended for three months without pay.
The pair made a series of offensive calls to Sachs, 78, on Brand's Radio 2 show which included obscene comments about the Fawlty Towers actor's 23-year-old granddaughter, Georgina Baillie.
The incident led Lesley Douglas, controller of Radio 2, to tender her resignation on Thursday.
The BBC is hoping to draw a line under the furore, which, as of last night, had attracted 37,500 complaints.
The Trust, the BBC's governing body, has asked for a further report into the matter.
It wants more information on how the programme was approved for broadcast and who was involved in the final decision.
Sir Michael, however, said he was satisfied with how the matter has been handled by Mark Thompson, the BBC's director general.
Jonathan Ross has been suspended for three months
Speaking on the BBC Breakfast programme, he said Mr Thompson had acted "with courage" and had the full confidence of the Trust.
"The BBC takes its responsibilities over standards seriously and recognises what happened was completely unacceptable."
Ofcom is conducting its own investigation into the row, which could result in a fine.
Mr Thompson, meanwhile, has said there must be "tight discipline" in the future and that "nothing like this must ever happen again".
He called Ross's actions "utterly unacceptable", adding that the presenter should regard his three-month suspension as a "final warning".
He said the suspension - which will reportedly cost the entertainer more than £1 million - was "an exceptional step".
Mr Thompson met the BBC Trust on Thursday to discuss the crisis.
Russell Brand resigned from his Radio 2 show
The Trust has demanded an on-air apology and called for editorial standards in the BBC to be tightened, with particular attention to "high risk" programmes.
In a statement issued after their meeting with Mr Thompson, the Trust said it was "dismayed" that the broadcasts "fell so far short of audience expectations".
It said there had been a "deplorable intrusion" into "the privacy of Mr Sachs and his granddaughter".
They issued an unreserved apology to licence fee payers, as well as to Sachs.
Ms Douglas said the decision to leave her job was "mine and mine alone" and was made with "enormous regret".
Her departure dismayed many of her colleagues, one of whom - DJ Chris Evans - called her "the best boss in the world".
However, he said employees of the station understood the "severity of what's gone on".
Lesley Douglas began her career at the BBC in 1986
"We don't feel like we've been picked on undeservedly," he said after his show on Thursday. "It was a huge mistake and we all wish it hadn't happened.
"Andrew Sachs doesn't want to be 78 years old and remembered for this. He wants to be remembered for what he did brilliantly."
Speaking on Five Live earlier, Radio 2 DJ Paul Gambaccini said Douglas's departure was a "tragedy Greek in its dimensions".
"She believed Russell Brand's hire was a good thing for Radio 2 and she stood by him through thick and thin.
"I knew it would end in tears. When you pick up a time bomb, one day it will explode."
The incident, he said, demonstrated the danger of "airlifting" TV personalities into radio.
"I believed Russell did not have the talent for Radio 2 and I've been proved right. I felt he was not appropriate for the network."