Transport for London has said a series of anti-Israel posters seen on tube trains across the capital are "unauthorised acts of vandalism".
The posters appeared in advertising slots on trains at the weekend ahead of the annual "Israel Apartheid Week" campaign which began on Monday.
They showed mocked-up versions of BBC reports and claimed the Corporation's coverage of Israel and the Palestinians was biased.
But Tfl said in a statement that the posters had not been authorised and were being removed.
A TfL spokesman said: “These are not authorised adverts. It is fly posting and therefore an act of vandalism which we take extremely seriously.
"Our staff and contractors are working to immediately remove any found on our network.”
The campaign claimed British-made arms were used to “massacre” Palestinians during Israel’s last operation against Hamas.
Posters the London underground were titled “Apartheid is Great Britain”.
Another image targeted security company G4S, which operates some prisons in Israel and the West Bank.
The posters accused the firm of “securing Israeli apartheid” and doing “whatever it takes to secure profits”.
Images on social media on Sunday suggested the adverts were part of a four poster campaign by activists.
It is thought more than 500 could have been posted, with anti-Israel activists claiming they would be on display to the tube's four million customers for the entirety of the apartheid week campaign.
A London Jewish Forum spokesman said: "These posters are awful smears that do nothing to contribute to peace and dialogue, placing significant strains on inter-community relations across London.
"They are an act of vandalism, seeking to undermine the UK's relationship with Israel and designed to foster discomfort. We welcome Transport for London's commitment to quickly remove them."
Conservative London Assembly member and transport spokesman Richard Tracey said: “It is utterly deplorable that these offensive ‘adverts’ have been smeared across parts of the tube network by a small number of activists.
“Racist and deeply insensitive propaganda will not be tolerated anywhere in our capital, let alone on our transport network, and I urge anyone who sees these posters to report them to TfL staff immediately.”
A BBC spokesperson said: “We are committed to reporting all aspects of a very complex conflict in a fair and balanced way, reflecting a range of voices.”
The posters caused a stir in Israel with Prime Minister Benjamin Netanyahu and MK Yair Lapid from Yesh Atid - who described the posters as "unacceptable" - claiming they were instrumental in Tfl's removal of the posters.
Mr Lapid said at a meeting in the Knesset today:"I contacted the Mayor of London, Boris Johnson, who is a friend of Israel and explained that the State of Israel found these things unacceptable, I asked him to intervene. He explained that they were put up without authorization and would give the instruction for them to be taken down immediately.”
Mr Netanyahu however disputed this saying that he had instructed Foreign Ministry director Dore Gold to deal with the issue.