The BBC committed a "significant breach" of industry standards by omitting to mention that the voice of a programme about the Gaza situation was the offspring of a Hamas official, according to British broadcasting authority Ofcom.
An probe by Ofcom into Gaza: How to Survive a Warzone has determined that the documentary was "significantly deceptive".
The chief executive of the broadcaster had earlier expressed regret, noting there had been "a significant failing in relation to accuracy".
The regulator has instructed the broadcaster to transmit a evening statement about its conclusions.
"Given this constitutes a significant violation of our code, we are directing the broadcaster to transmit a announcement of our findings against it on BBC2 at nine o'clock in the evening, with a schedule to be determined," the regulator stated.
'Risk to Damage Trust'
The watchdog's announcement stated: "Our investigation concluded that the programme's lack of disclosure that the presenter's father served in a role in the Hamas-administered government was significantly deceptive.
"It meant that the viewers did not have essential details which may have been very significant to their assessment of the voice and the content he provided.
"Credibility is at the heart of the connection between a television network and its public, particularly for a state-funded media outlet such as the BBC.
"This failing had the possibility to damage the exceptionally strong degrees of confidence that audiences would have invested in a documentary produced by the BBC about the Gaza conflict."
The film was withdrawn from the BBC's streaming service in last February after the presenter's familial connections were revealed, and in this past July an corporation's own inquiry concluded it violated the broadcaster's content policies on truthfulness.
A corporation official said: "The authority's determination is in agreement with the findings of the internal assessment, that there was a major oversight in the documentary in relation to the broadcaster's journalistic policies on truthfulness, which corresponds to clause 2.2 of the authority's broadcasting regulations.
"We have apologised for this and we comply with the authority's determination in full. We will follow the penalty as soon as the schedule and wording are finalised."
