The High Court of Justice this week refused to release convicted spy Marcus Klingberg, saying that the ailing Israeli could still endanger national security.
The Polish-born Klingberg, 77, has served 12 years of an 18-year sentence for spying for the former Soviet Union.
Klingberg, who has had several strokes recently, had appealed to the court for an early release on account of his poor health.
But the court said Sunday that Klingberg might still remember information that could bring harm to the Jewish state.
Klingberg was arrested and secretly sentenced in 1983. His case first surfaced in the British media in 1987, and later in German reports.
An Israeli news blackout was lifted in 1993, though details about the case and his capture remain unclear.
According to Israeli reports, Klingberg immigrated to Israel in 1948, and was last seen in January 1983 en route to a scientific convention in Western Europe.
At the time, he was head of a research facility in the center of the country.
The Archive of the Jewish Telegraphic Agency includes articles published from 1923 to 2008. Archive stories reflect the journalistic standards and practices of the time they were published.