Security measures at the BBC have been "sharpened up" after its head of news received death threats from a man claiming to be a Serbian activist.
The BBC's news chief executive, Mr Tony Hall, and his family are now under police protection, and detectives investigating the murder of the BBC presenter Jill Dando at her home in Fulham on Monday are considering a possible link between her killing and the death threats.
ITV reported last night that a "Serb source" wrote to Ms Dando two weeks before she was murdered to complain about her appearance in a TV charity appeal for refugees from Kosovo. The letter was sent to Ms Dando's office, according to ITV's Tonight With Trevor McDonald programme. 995690
Mr Hall has received three death threats, and in one call to the BBC's switchboard on Tuesday a man claimed he was responsible for Ms Dando's murder. He said her murder was in retaliation for NATO's attack on a Serbian television station last week.
As police continued to search for clues that might lead them to a motive and the identity of Ms Dando's killer, security guards at Broadcasting House searched visitors' bags and checked identity tags.
"We have sharpened up some of the aspects of security with extra commissionaires and also advising staff. We have pretty tight security measures in any case but in light of current events we are reassessing them on a day-to-day basis," a BBC spokeswoman said.
The Foreign Secretary, Mr Robin Cook, said he was assured that the security services and the police would take appropriate action if they considered a journalist was under threat of attack. "I'm sure the police are taking all leads and all theories seriously. Our security services are very efficient," he said.
Asked if individuals planning revenge attacks would be detained, as some were during the Gulf War, Mr Cook said: "I'm quite sure our security forces have this under review. If they have evidence that anybody from any part of the world may be contemplating action which breaks the law, they have powers to act."
As more floral tributes were placed near Ms Dando's home yesterday, her fiance's parents, Dr John Farthing and his wife, Barbara, paid a moving tribute to "a fantastic and loving person".
British police yesterday announced their first possible breakthrough in one of two racially motivated nail-bomb attacks in London, releasing images of a suspect they asked the public to help identify. The closed-circuit television images show a white man in a white baseball cap and dark zipup jacket walking through Brixton at about the time of the blast on April 17th.
Police said they had strong reasons to consider him a suspect.