An Israeli man described as a member of an ultra-Orthodox fringe group and accused of offering to spy for Iran was jailed for four and a half years, court papers showed.

Isaac Bergel contacted Iran's embassy in Berlin in 2011 offering to provide information about Israel, prosecutors said. He had kept in touch with Iranians, using the Internet and public telephones, the court heard.

Bergel, born in 1966, was originally accused of treason. But, under a deal with legal officials, he admitted to lesser charges of contact with a foreign agent and showing intent to betray his country, the court papers said.

At the time of Bergel's arrest in July, Israeli officials said he belonged to the Neturei Karta ultra Orthodox group that rejects Israel's existence, believing a Jewish state may exist only after the Messiah comes.

Israel has accused its arch-foe Iran of working to develop a nuclear bomb to threaten the Jewish state. Iran insists its nuclear programme is purely for peaceful purposes.