The BBC committed a "major breach" of industry standards by omitting to mention that the narrator of a film about the Gaza situation was the offspring of a Hamas official, according to British broadcasting authority Ofcom.
An investigation by the media regulator into Gaza: How to Survive a Warzone has found that the programme was "materially misleading".
The head of the BBC had previously apologised, saying there had been "a serious error in relation to factual correctness".
The regulator has ordered the BBC to transmit a evening declaration about its decisions.
"Given this constitutes a serious breach of our code, we are ordering the corporation to transmit a message of our determinations against it on BBC Two at 9pm, with a timing to be confirmed," the statement read.
'Potential to Undermine Credibility'
The authority's announcement stated: "Our investigation concluded that the programme's lack of disclosure that the presenter's male guardian held a position in the Hamas-controlled administration was substantially inaccurate.
"Consequently that the audience did not have vital facts which may have been extremely pertinent to their evaluation of the presenter and the information he provided.
"Credibility is at the core of the connection between a television network and its public, especially for a national broadcasting corporation such as the British Broadcasting Corporation.
"This oversight had the possibility to undermine the significantly high degrees of confidence that audiences would have placed in a BBC factual programme about the Gaza conflict."
The documentary was withdrawn from the BBC's streaming service in February after the narrator's family links were revealed, and in July an corporation's own inquiry concluded it breached the organization's editorial guidelines on truthfulness.
A corporation official stated: "The Ofcom ruling is in line with the findings of the corporation's inquiry, that there was a significant failing in the film in relation to the corporation's content standards on factual correctness, which corresponds to Rule 2.2 of the authority's broadcasting regulations.
"We expressed regret for this and we accept the regulator's ruling in complete. We will follow the directive as soon as the date and wording are finalised."
