Jeremy Corbyn described Israel's politicians as "criminals" and called for trade sanctions to be imposed on the Jewish state in a series of letters written before he became leader of the Labour Party and published by the government on Wednesday.

In one of the letters, Mr Corbyn attacks Israel's "victimisation of the people of Palestine" and calls for the UK to "penalise Israel via the most obvious method".

The publication of the letters, released following a Freedom of Information request, will accentuate concerns over widespread Israel-hate and antisemitism among Labour party members.

In one letter addressed to former foreign secretary William Hague, written on behalf of the Palestine Solidarity Campaign, Mr Corbyn comments on his experiences during a visit to Gaza.

He writes: "At one of the meetings I was asked a) if we would stop allowing Israel's criminal politicians to come to our country freely b) if we would ensure that the BBC portray Palestine fairly."

He adds:"Had I not been working towards all of these [...] aims I'd have hung my head in shame."

Mr Corbyn also described Gaza as "one huge and suffering refugee camp," adding: "Without Unwra [the UN refugee agency] as well as the illegal tunnel trade that has evolved out of desperation, no one would survive."

The tunnels mentioned by Mr Corbyn were regularly used by Hamas to import rockets that have been used against Israeli towns and cities.

In the same letter, dated 27 February 2013, Mr Corbyn attacks the "unjustness of the administrative detention used against the Palestinians", and asks the foreign secretary to give the matter his "urgent attention".

In another letter to Mr Hague, written on March 27 2011, Mr Corbyn accuses then Middle East minister Alistair Burt of "lack of balance" in his statement on the escalating conflict in Gaza.

Mr Corbyn wrote: "He [Burt] is aware in recent days that Israeli military action has resulted in significant loss of life and injuries. He may also be aware that this recent escalation began when Israel launched a mortar shell attack on Gaza on February 23."