A terrorist jailed for 45 years for plotting to blow up an Israeli airliner has lost a legal battle to secure his release, the BBC understands.
The Parole Board rejected Jordanian Nezar Hindawi's bid for early release, despite previously recommending it.
Hindawi, 57, planted a bomb in his unwitting pregnant fiancee's hand luggage on a flight from London Heathrow to Tel Aviv in 1986.
The device could have killed 375 people had security staff not found it.
A three-member Parole Board panel, headed by a judge, held an oral hearing in December and decided that it was not yet safe for Hindawi to be let out. He was informed last week.
A board spokesman said the only legal question it had to answer was whether there was a risk of a further offence taking place during the "parole window".
He said that had to be weighed against the benefits to both the prisoner and the public of a longer period of testing on parole.
He added that the nature of the "index offence", the prisoner's offending history, their progress in prison, and statements and reports from victims, psychologists, probation officers and prison officers would all be taken into account.
Hindawi's lawyer Daniel Guedalla declined to comment on the decision.
In 2009, the board had concluded that Hindawi should be freed, saying he had shown remorse and was "very unlikely" to re-offend.
But then-Justice Secretary Jack Straw, and his successor Ken Clarke, sought to block Hindawi's release arguing he had not rejected terrorism.
In April last year the High Court ruled that the ministers' decision had been "flawed" because it was based on official papers that did not present a "balanced" case.
The case went back to the Parole Board to reconsider.
Hindawi is believed to be Britain's longest-serving prisoner on a fixed sentence.
He first became eligible for parole in 2001, a third of the way through his sentence.
He is entitled to have his parole request reconsidered within 12 months, and will be automatically freed in May 2016, at the two-thirds point of his sentence.
He will be deported to Jordan at the end of his sentence.
Hindawi was jailed for hiding Semtex explosive in the luggage of his pregnant fiancée, Irishwoman Anne-Marie Murphy, then 32, without her knowledge.
He was from a wealthy Palestinian family whose village was burned in the Israeli-Arab war of 1967, when he was 12.
After his family became refugees in Jordan, he joined the Palestine Liberation Organisation (PLO), became a writer and travelled to London.