The chairman of the Jewish National Fund has responded to a personal attack on him by the pro-Palestinian Jewish campaigner Tony Greenstein.

Mr Greenstein, a long-time anti-Zionist, implied in a letter to the Guardian newspaper that JNF UK’s chairman Samuel Hayek had been lying for his country.

On October 7 Mr Greenstein was one of the signatories to a letter calling for Ed Miliband to break the tradition, set by former Labour leaders Tony Blair and Gordon Brown, of being a patron of the JNF.

The letter accused the JNF of being “actively complicit in the ethnic cleansing of Palestinians”.

It said that Mr Miliband should break with the organisation to show that his prior criticisms of Israeli policy were not “empty words”.

In response, Mr Hayek wrote that the letter had been “misconceived in its approach and inaccurate in its content.” He pointed out that the JNF’s focus since its creation had been developing and sustaining the environment in Israel and that current projects in the Negev reflect this.

Mr Hayek called the accusation “a distortion of the truth on the grandest of scales.”

He added: “Our environmental and humanitarian work is not based on any political or religious affiliation, but rather on supporting Israel and its population – whatever their background.

“This was the case before the modern state of Israel was created and will continue to be the case long into the future.”But in a further letter, Mr Greenstein said the response was “disingenuous”.

He said: “The JNF's focus, from the day it was established, was to purchase land for Jewish settlers and to alienate it from the Arab peasants who tilled the land.”Last week it emerged that Mr Greenstein had attempted to rig a JC poll asking whether rabbis should work with the English Defence League.

On the "Boycott Israel Network" he wrote: “Please try to make sure that people on BIN vote and to vote yes. It will be quite good for us that a JC poll comes out in favour of working with the EDL.”