The BBC was fined £95,000 today for running unfair competitions on two radio stations.
Industry regulator Ofcom imposed the penalty for "serious" breaches of its code in shows broadcast on Radio 2 and BBC London 94.9FM.
The BBC invited listeners to take part in phone-in competitions in pre-recorded programmes that were broadcast "as live" when it knew they stood no chance of winning, Ofcom said.
The regulator fined the corporation £70,000 over editions of Dermot O'Leary's Radio 2 show broadcast between June and December 2006.
And it ordered it to pay £25,000 for breaches in Tony Blackburn's BBC London programme between December 2005 and December 2006.
The BBC must also broadcast a statement of Ofcom's findings on both the stations.
Ofcom said: "The BBC invited listeners to enter these competitions at the time of the broadcasts, in the full knowledge that the audience stood no chance of either entering or winning.
"However, it was noted that these competitions were not run for profit.
"Ofcom also recognises the extensive steps the BBC has taken to ensure future compliance in this area."
The programmes breached rule 2.11 of Ofcom's broadcasting code, which relates to the fair conduct of listener phone-in competitions.
The corporation's governing body, the BBC Trust, said it regretted the loss of licence fee payers' money as a result of the breaches.
The Trust's editorial standards committee (ESC) considered the broadcasts and concluded they were serious and involved "audience deception".
In a statement, the Trust said: "In 2007 the Trust had made clear that 'the culture of the BBC must be such that any proposal to mislead audiences is instantly dismissed as wholly inappropriate'.
"These cases pre-dated that statement but should not have occurred.
"The ESC was satisfied that the cases did not raise new issues which had not been previously addressed, and was satisfied that the remedial steps taken by the BBC over 2007 and 2008 have put in place protections which should prevent cases of this nature in the future."
The on-air apologies will be broadcast at about 2pm on Saturday on both radio stations.
Today's findings conclude Ofcom's investigations of audience participation in BBC programmes broadcast up to and including 2007.
The BBC's management said it accepted the findings of Ofcom and the BBC Trust.
In a statement it said: "These historical breaches were tackled by a comprehensive action plan launched by the BBC in July 2007.
"This included a major programme of training for over 19,000 staff, a new specialist unit to provide advice on all technical aspects of running competitions, and a strict new code of conduct.
"We welcome Ofcom's recognition of the extensive action taken to address these issues and that neither the BBC nor any member of staff made any money from these lapses."
Ofcom hit the BBC with a record £400,000 fine in July for duping viewers in flagship shows including Comic Relief and Sport Relief.
At the time the regulator described the breaches as "very serious", saying: "In each of these cases the BBC deceived its audience by faking winners of competitions and deliberately conducting competitions unfairly."
Ofcom criticised BBC executives for not immediately giving it full details of the latest breaches when the corporation carried out "trawls" of its programmes in March and July last year.
These internal investigations were launched in response to concerns about broadcasters' misuse of premium-rate phone lines for competitions and voting.
Ofcom's content sanctions committee said it was "wholly unacceptable" that senior BBC managers made their own judgment of how serious the Radio 2 and BBC London cases were.
The committee said: "It was a matter of significant concern to the committee that at the time of the 'trawls', the BBC had considered the breaches in this case to be of a 'less serious' nature than it now accepted.
"The committee noted that the criteria imposed by the BBC on the results of its 'trawls' were limited to those instances where programme makers had posed as competition winners or used fictitious names as winners on air.
"The committee accepted that the investigations undertaken by the BBC during and following its 'trawls' had been extensive.
"Nevertheless, the committee was particularly concerned that the BBC's senior management had admitted it had been aware at the time of its investigations that the conduct in this case involved repeated breaches of Ofcom's code.
"It was a matter of significant concern to the committee that the BBC's senior management had taken a decision to judge the seriousness of the case, by means of its own criteria, despite knowing at the time that it involved breaches of the code, with which the broadcaster has a statutory obligation to comply."
The BBC Trust raised the same issue, saying the two cases should have been reported to it last year after the corporation's trawls.
It said in its report: "The ESC also concluded it should have asked for further and better details of the cases not singled out for specific reporting by the executive at the time.
"In future, the executive was asked to inform the ESC of all serious breaches and if in doubt to err on the side of caution."Reuse content