Broadcasting watchdog Ofcom has said it has launched investigations into ITV1's This Morning and BBC's Newsnight after complaints the shows breached "generally accepted standards".
The shows are also under scrutiny for "the application of standards to prevent unfair treatment to an individual, and unwarranted infringements of privacy".
The programmes involved are the November 2 Newsnight which wrongly implicated Lord McAlpine in a paedophile ring that targeted children at a care home in Wrexham in north Wales, and the November 8 This Morning where presenter Phillip Schofield confronted David Cameron with a list of alleged paedophiles.
An Ofcom spokesman confirmed it had received 415 complaints about This Morning and four about the Newsnight programme.
The BBC is thought likely to reach a financial settlement with Lord McAlpine after apologising to the peer.
ITV said earlier that it has taken "appropriate disciplinary action" over the incident which saw Schofield roundly criticised for handing the Prime Minister a list of names - understood to be Conservative Party figures - during the live show which he said he had put together from internet rumours.
An ITV spokesman said: "We sincerely apologise because the way in which the issue was raised was clearly wrong and should have been handled differently. We have taken steps to make sure our editorial processes are always properly followed, which was not the case in this instance, and to ensure such an error will not be made again."
The presenter was later forced to apologise after the list was briefly exposed on screen raising fears individuals could be identified. After being handed the list, which Schofield assembled after trawling the internet for three minutes, the Prime Minister warned online discussions of an alleged paedophile ring could degenerate into a "witch-hunt" against people who are gay.
The Guardian reported ITV's "disciplinary action" was taken against Schofield and three production staff but the broadcaster refused to comment further. Schofield presented Thursday's edition of the show as normal.
Conservative John Whittingdale, chairman of the Commons Culture, Media and Sport Committee, has written to Peter Fincham, director of television at ITV, calling for information about who was involved in the decision to hand the list of names to the Prime Minister.