After the episode aired, it was removed from ITVX and re-uploaded on Wednesday with the watermelon symbol removed from Bromley’s T-shirt.
A spokesman for Big Brother said it did not “allow any personal items into the house that could be deemed harmful”.
“We regret that the implications of this particular item of clothing were not fully understood in our bag checks or prior to broadcast of last night’s show,” the broadcaster said.
“We apologise to any viewers who have been offended by the broadcast and assure viewers that Big Brother was unaware of the implications of the image.”
It added that the item of clothing had now been removed from the house and the housemate “expressed that they are unaware of the implications and did not wish to cause any harm or offence”.
Tuesday’s episode of Big Brother Late & Live was also edited to remove the footage of Bromley wearing the top.
More than 42,000 Palestinians have been killed since the Hamas attack on 7 October, in which around 1,200 people were killed and 251 taken hostage.
The watermelon symbol is synonymous with the pro-Palestinian movement as the colours of the fruit are the same as those on the Palestinian flag.
Following Tuesday’s episode, charity Campaign Against Antisemitism said it had submitted a complaint to Ofcom as the “incident represents a serious violation of broadcasting standards”.
In a statement on X, the organisation said the graphic was anti-Semitic and “caused significant distress among the British Jewish community, who regard it as a genocidal message similar to the slogan From the River to the Sea which calls for the elimination of the world’s only Jewish state.”
The Palestine Solidarity Campaign and other activists contest this, saying the slogan refers to “the right of all Palestinians to freedom, equality and justice”.