The BBC has suspended all phone-in competitions after uncovering a string of viewer deceptions involving Children In Need, Comic Relief and Sports Relief.
All three charity appeal programmes featured fake competition winners. Shows on the World Service, children's channel CBBC and radio station 6 Music also duped the public.
The six new cases came to light after BBC director-general Mark Thompson ordered an internal investigation in the wake of the royal row over a BBC1 trailer which wrongly implied the Queen had stormed out of a sitting with photographer Annie Leibovitz.
He presented his findings in a meeting with the BBC Trust, which had demanded an explanation over the royal fiasco. The Trust called the editorial breaches "deeply disappointing" and ordered an immediate inquiry.
Mr Thompson said the deceptions were "totally unacceptable" and declared: "The behaviour of a small number of production staff who have passed themselves off as viewers and listeners must stop.
"We must now swiftly put our house in order." But he repeatedly dodged questions about whether he or any other senior BBC executives should resign. And he risked accusations of trivialising the matter by referring to the use of fake winners as a "white lie".
Mr Thompson insisted the mistakes were not made out of personal gain or intended malice, but occurred mainly as a result of technical hitches. "We have had a rude awakening. It is clearly a grave matter but the right thing to do is to take steps to make sure we close these gaps," he told BBC News 24.
"A group of people have taken it upon themselves to carry out this kind of white lie. It is not acceptable, it is better to come clean - the public will understand."
Asked on Sky News if he was considering resignation, Mr Thompson replied: "My task today is not to think about my own position but to roll up my sleeves with the rest of the BBC and make sure we sort it out."
The six fresh cases follow the revelation that Blue Peter persuaded a child to pose as a competition winner, which resulted in a £50,000 fine by regulator Ofcom.
The Comic Relief incident occurred on March 16 this year, two days after the Blue Peter con came to light. Viewers were invited to ring in for the chance to win prizes belonging to a famous couple, with money from the calls going to charity. The successful "caller" was a member of the production team.
A Sport Relief phone-in in July 2006 featured a similar scenario.
PA