Secrets emerge of Vanunu's prison life: Recently released Lebanese tells Robert Fisk about stringent conditions in jail where the nuclear technician is being held

MORDECHAI VANUNU, the convicted Israeli nuclear technician, stands at the window of his tiny cell at Ashkelon and shouts 'I love Arafat - I love the PLO' to stunned Palestinian prisoners in the courtyard below. Marcus Klingberg, the Israeli spy and germ-warfare specialist, hoards pills from the jail medical dispensary until he can take an overdose - only to have his life saved by prison guards, who use a stomach pump on the 76-year would-be suicide in the jail clinic.

A mysterious third Israeli, convicted by his country of spying two years ago, paces the exercise yard in isolation, wearing a round fishing hat, a man without a name whose crime is unknown even to his fellow prisoners.

This remarkable glimpse of the world inside Israel's high-security prison at Ashkelon, home to 622 Palestinians, 16 Lebanese and the three Israelis, has been revealed for the first time this week by a former inmate, a Lebanese jailed in Israel 11 years ago for planning an attack on Jewish targets inside the occupied West Bank. He has just been released and returned to Beirut with the assistance of the International Red Cross.

The testimony of 36-year-old Jamal Mahroum, whose identity and place of imprisonment have been confirmed by humanitarian agencies, contains details not only of the jail conditions of Vanunu - sentenced in 1986 to 18 years solitary confinement for leaking details of Israel's nuclear weapons manufacturing plant to the Sunday Times - but also of the security measures that drove Klingberg to attempt suicide on three separate occasions. Of the third Israeli prisoner, Mr Mahroum knew only that he had been a researcher in a scientific department of the Israeli Defence Ministry in Tel Aviv.

'They close all the doors and gates around the prison when Vanunu goes to the exercise yard above the isolation cells - no one is allowed to talk to him, not even the guards,' Mr Mahroum said yesterday. 'He is allowed two hours in the yard every day but he is alone and in silence. The only Israeli guard who is permitted to talk to him is an officer called Abu Kara, a Moroccan Jew, who takes care of him, watches him, checks his food and letters and everything he touches. The guards call Vanunu 'Johnny' - it's a nickname that's meant to make fun of him, I think because he became a Christian.'

On one occasion two years ago, however, a mistake by prison guards suddenly gave Vanunu access to his fellow inmates. 'After Vanunu had taken his exercise, we would go to the same yard,' Mr Mahroum recalled. 'But this time, our guards apparently thought Vanunu was back in his cell and let us out - and there he was, walking towards us. He was smiling and he put his finger to his lips and said, 'Please say nothing - just let me walk with you. I want to walk with other people. I am lonely.'

'So we walked with him, maybe for 10 minutes, and he thanked us and smiled - he always smiled. Then the Israelis discovered what they had done and sounded the alarm and many guards came with riot gear and sticks and took him away. That night, he came to his cell window and shouted to us: 'I love Arafat - I love the PLO.'

Vanunu, Mr Mahroum said, tries to keep fit, always wearing sports shoes and shorts, running and performing gymnastics, in contrast to Klingberg, whose lonely shuffling round the exercise yard at night after a hernia operation touched even hardened Palestinian prisoners. 'The Israelis called Klingberg 'Abraham Greenberg' and told him not to reveal his real name to us - but he did and I talked to him many times over eight years,' Mr Mahroum said. 'I was in a cell at one corner of the yard and he would walk slowly past and we'd exchange a few words in English. Each time he made a round of the yard, he'd say a sentence or two and I'd reply. It could take three or four hours to complete a conversation.'

The Israelis acknowledged only last year that they were holding Klingberg, a decade after a secret court sentenced him to 18 years imprisonment for spying for the Soviet Union. The revelation was regarded by many in Israel as a tacit admission that their country had been developing chemical and biological weapons - just as Vanunu had provided proof that Israel possessed nuclear weapons.

'Klingberg was a very sick man,' Mr Mahroum said. 'He told me how he was a soldier in the Soviet Army in the Second World War, how his daughter lived in France with her child. One night he came near my cell window and just said: 'I am alone'. I said: 'But you've been in solitary for years.' And he replied: 'No, I've just heard that my wife is dead - now I am truly alone.' We felt very sorry for him.'

Klingberg repeatedly complained about his loneliness to the guards and, when they failed even to reply to him, he made the first attempt on his life, according to Mr Mahroum. 'He told me he went into the bathroom where there is a space above the partition and he climbed on the partition and threw himself head first into the empty bath. But he did not break his neck. So he started going to the nursing clinic for pills for stomach aches but he took the pills away each time and hoarded them in his cell. And when he had collected a lot of pills, he swallowed them all. But the guards came and pumped his stomach and he survived. He tried to kill himself a third time. After that, the guards gave him more exercise time.

'Above all, he wanted to have his sentence reduced so he could die a free man. An Israeli government commission visited Ashke lon prison to see him. When I left the prison, he was the last prisoner I shook hands with. He said he was happy for me because I was going home, and I wished him luck. But he was angry and said to me: 'Those bastards have refused my appeal'.'

The prison authorities have allowed Klingberg and Vanunu to watch television and read books. 'One of the last books I saw Klingberg reading was about the Palestinian Hamas Islamic group,' he said. 'He told me he knew one of the Hamas leaders called Salah and when I asked him how, he said: 'Well, here's his picture in the book - and I recognise him because he's locked up in the cell over there'.'

(Photographs omitted)