The BBC committed a "significant breach" of media regulations by not revealing that the narrator of a film about Gaza was the child of a Hamas representative, as ruled by British broadcasting authority Ofcom.
An probe by the media regulator into the documentary titled Gaza: How to Survive a Warzone has found that the programme was "significantly deceptive".
The BBC's director general had earlier expressed regret, noting there had been "a serious error in relation to factual correctness".
The authority has ordered the broadcaster to transmit a evening announcement about its decisions.
"As this represents a major infringement of our rules, we are ordering the BBC to transmit a announcement of our conclusions against it on BBC Two at 21:00, with a timing to be finalised," it said.
'Potential to Undermine Confidence'
The watchdog's statement said: "The inquiry we conducted concluded that the documentary's lack of disclosure that the narrator's male guardian occupied a role in the Hamas-controlled authority was significantly deceptive.
"This implied that the audience did not have essential details which may have been very significant to their assessment of the voice and the information he provided.
"Credibility is at the core of the bond between a broadcaster and its viewers, particularly for a public service broadcaster such as the BBC.
"This error had the risk to undermine the exceptionally strong amounts of credibility that viewers would have put in a factual film from the broadcaster about the conflict in Gaza."
The film was removed from the online platform in last February after the presenter's familial connections emerged, and in July an broadcaster's internal assessment concluded it violated the organization's editorial guidelines on accuracy.
A BBC spokesperson commented: "The Ofcom ruling is in accordance with the conclusions of Peter Johnston's review, that there was a serious error in the programme in relation to the broadcaster's journalistic policies on accuracy, which corresponds to Rule 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we agree with the authority's determination in full. We will follow the penalty as soon as the schedule and wording are determined."
