The BBC committed a "significant breach" of industry standards by omitting to mention that the narrator of a programme about the Gaza situation was the offspring of a Hamas official, as determined by British broadcasting authority Ofcom.
An investigation by Ofcom into the programme Gaza: How to Survive a Warzone has concluded that the documentary was "significantly deceptive".
The BBC's director general had previously apologised, saying there had been "a major oversight in relation to truthfulness".
Ofcom has ordered the corporation to broadcast a peak-time declaration about its decisions.
"Since this amounts to a major infringement of our regulations, we are directing the corporation to air a announcement of our conclusions against it on the BBC's second channel at 21:00, with a date to be determined," the regulator stated.
'Possibility to Undermine Credibility'
The authority's statement declared: "Our probe determined that the programme's lack of disclosure that the presenter's parent held a position in the Hamas-run administration was significantly deceptive.
"It meant that the audience did not have essential details which may have been extremely pertinent to their judgment of the voice and the details he presented.
"Confidence is at the core of the bond between a television network and its viewers, notably for a state-funded media outlet such as the BBC.
"This error had the risk to damage the very considerable amounts of credibility that viewers would have invested in a BBC factual programme about the Israel-Gaza war."
The programme was removed from the online platform in February after the presenter's familial connections came to light, and in the month of July an broadcaster's internal assessment concluded it infringed the corporation's editorial guidelines on factual correctness.
A corporation official stated: "The authority's determination is in accordance with the results of Peter Johnston's review, that there was a serious error in the programme in relation to the BBC's Editorial Guidelines on accuracy, which corresponds to regulation 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we comply with the regulator's ruling in complete. We will adhere to the penalty as soon as the timing and language are finalised."
