The BBC was found to have committed a "major breach" of broadcasting rules by omitting to mention that the voice of a documentary about the Gaza conflict was the child of a Hamas official, according to regulatory body Ofcom.
An probe by Ofcom into the programme Gaza: How to Survive a Warzone has found that the documentary was "materially misleading".
The head of the BBC had already issued an apology, stating there had been "a major oversight in relation to truthfulness".
The regulator has ordered the BBC to air a peak-time declaration about its conclusions.
"Given this constitutes a serious breach of our regulations, we are ordering the corporation to transmit a statement of our findings against it on BBC Two at 9pm, with a date to be determined," it said.
'Risk to Erode Credibility'
The watchdog's statement stated: "Our investigation concluded that the programme's omission to reveal that the voice's parent served in a role in the Hamas-run government was significantly deceptive.
"This implied that the viewers did not have essential details which may have been highly relevant to their judgment of the presenter and the information he provided.
"Credibility is at the heart of the connection between a media organization and its viewers, particularly for a state-funded media outlet such as the British Broadcasting Corporation.
"This failing had the risk to erode the exceptionally strong degrees of confidence that viewers would have invested in a documentary produced by the BBC about the Gaza conflict."
The programme was removed from iPlayer in the month of February after the presenter's personal associations emerged, and in July an broadcaster's internal assessment determined it violated the broadcaster's content policies on factual correctness.
A corporation official stated: "The regulator's decision is in agreement with the results of Peter Johnston's review, that there was a serious error in the documentary in relation to the BBC's Editorial Guidelines on truthfulness, which reflects Rule 2.2 of Ofcom's Broadcasting Code.
"We have apologised for this and we accept Ofcom's decision in complete. We will follow the penalty as soon as the schedule and language are determined."
