Mordechai Vanunu, the man who revealed Israel's nuclear secrets to the world, was yesterday jailed again by a Jerusalem court for talking to foreigners in breach of his parole conditions.

The sentence follows a conviction in April for breaching his conditions 14 times by making contact with foreigners and travelling to Bethlehem at Christmas.

Vanunu, a former technician at Israel's Dimona nuclear plant, was first jailed in 1986 after he disclosed information about Israel's nuclear programme to the Sunday Times.

He was kidnapped in Italy and flown to Israel by agents of the Mossad, Israel's equivalent of MI6, after being persuaded to travel from London to Rome in a "honey trap".

He was jailed for 18 years and was released in 2004 but banned from leaving the country.

In his ruling yesterday, Judge Yoel Tzur wrote that it was "not easy" to sentence Vanunu to more prison time, "especially since the accused served a long prison sentence in the past, most of it in solitary confinement".

But, Mr Tzur wrote, "it appears that the accused displayed total disdain" for the restrictions imposed on him.

Vanunu's defence team said before the conviction that the terms of their client's parole order were unreasonable and depended on the theory that Vanunu still retained top secret information from his work at Dimona more than 20 years ago.

Vanunu's lawyer, Michael Sfard, said the prosecution had not suggested that anything that Vanunu had said in all of the conversations had in any way been damaging to the security of the state. He said that Vanunu was being jailed for a purely formal breach of his release conditions.

Mr Sfard said that he had also told the court that sending Vanunu back to prison was unnecessarily harsh, considering the punishment he had already suffered.

"If they want to make him a martyr, then that is the way to do it," he said.

Vanunu had found it very difficult to get work, said Mr Sfard, and felt very isolated.

Avigdor Feldman, another of Vanunu's lawyers, told reporters after the hearing that the limitations placed on Vanunu "had no equal in any other democratic country" and called the sentence "unreasonable".

After the verdict was announced, Vanunu said that his conviction proved that Israel was still ruled, in effect, by the British mandate, because the law under which he was convicted is from that era.

"Maybe I need to turn to the Queen or to Tony Blair in order to grant me justice," he said.

Vanunu was given a six-month jail term and a six-month suspended sentence.