Israeli police have arrested a British journalist who interviewed Mordechai Vanunu - the man jailed for revealing Israel's nuclear secrets - in 1986.
Peter Hounam (left) with Mr Vanunu's adoptive parents
The arrest of Peter Hounam, 60, has been confirmed by the Israeli prime minister's office.
Mr Hounam was making a documentary for the BBC, which said it was aware he had been arrested and was "very concerned".
Mr Vanunu, 50, was released from an Israeli prison in April after serving an 18-year jail sentence for spying.
Under the terms of his release, Mr Vanunu was forbidden from giving interviews, meeting foreigners and discussing his work as a technician at Israel's nuclear reactor in Dimona.
The BBC has not released any information on the documentary Mr Hounam was making and no details of his arrest have been released because of an Israeli government gagging order.
A UK Foreign Office spokesman said: "We have been informed that a journalist may have been arrested and our consular staff are looking into it."
Mr Hounam exposed Israel's atomic secrets in a Sunday Times article in 1986 which followed his interview with Mr Vanunu.
Vanunu was released in April after an 18-year jail sentence
The nuclear technician was subsequently arrested by Israeli security services in a sting operation.
Currently, he cannot leave Israel as the authorities say he still possesses state secrets but the 50-year-old says he has nothing to reveal.
Sunday Times foreign editor Sean Ryan said Mr Hounam, who lives in Perthshire, Scotland, had been in Israel to cover Mr Vanunu's release for the newspaper.
"I understand he has been arrested and he has been taken away from his hotel.
"We are trying to establish exactly what the situation is, where he is now and why he has been detained," Mr Ryan added.