David Cameron has been asked to follow through on his pledge to monitor the actions of a UN official who posted an antisemitic cartoon on a blog.

Last October, Mr Cameron “strongly condemned” UN Special Rapporteur Richard Falk. “Any further actions or comments Mr Falk may make” would be “closely watched”, he said. Last Friday, Mr Falk wrote that he believed “the US government and the organised Jewish community were responsible for the massive and enduring confiscation of Palestinian land and rights”.

Hillel Neuer, executive director of the UN Watch monitoring group, accused Mr Falk of “promoting racist remarks”. He has written to Mr Cameron with details of this latest outburst.

But Mr Falk said: “I have often opposed policies including those of the US and Israel… but to conflate such stands with racism is [part of] a wide-ranging and frequently repeated denunciation of my views and activities.”