Azam Azam, an Israeli-Arab belonging to the Druze sect, was convicted of working as a spy when he was employed in a textile plant in Egypt. He was accused of planning to send back information written on invisible ink on items of lingerie made in the factory.
Benjamin Netanyahu, the Israeli prime minister, protested by telephone to Hosni Mubarak, the Egyptian president, that Mr Azam was innocent and said that the verdict was "an outrage". Mr Azam's lawyer said that his client was the victim of poor political relations between Egypt and Israel.
Three accomplices of Mr Azam, Emad Abdel Hamid Ismail, an Egyptian, and two Israeli Arab women - Zahra Youssef Greiss and Mona Ahmed Shawahna - were given life sentences in absentia on the same charges. The trial became the focus of Egyptian hostility to Israel, which has intensified since Mr Netanyahu became prime minister last year.
The espionage charges mainly involved economic spying, according to the charges brought against Mr Azam, who was employed by one of the few Israeli- Egyptian joint ventures in Cairo.
Mr Azam's brothers, who were in court, earlier had said that their brother would be acquitted. Israel has repeatedly denied the charges were true and the case has been portrayed by the Israeli government and media as an officially inspired fabrication. However, there is no doubt that Egyptian popular animosity to Israel has grown. Mr Azam's Egyptian attorney, Farid el-Deeb, was denounced as a traitor by other Egyptian lawyers. The Egyptian press portrayed Mr Azam and Mr Ismail as spies long before the verdict was announced.
In Israel the government reacted strongly. David Bar-Ilan, the Prime Minister's aide, said: "The Prime Minister said in the cabinet meeting that this is an outrage. Azam Azam is innocent. He does not deserve to spend one day in jail."
Mr Netanyahu has been lobbying Mubarak to release Azam since he was arrested in November 1996.