Director general Tony Hall said to be under guard after allegation of threats to kill following sacking of Jeremy Clarkson

Scotland Yard says it is investigating alleged threats to kill the director general of the BBC, Tony Hall, as the fallout over the decision to sack the Top Gear presenter Jeremy Clarkson took a sinister turn.

According to the Mail on Sunday, the BBC’s head of security put out an urgent appeal for ex-Special Forces personnel to take part in an operation to protect Lord Hall, said to cost to licence payers more than £1,000 a day.

A security source told the paper: “There was a sudden urgency on Wednesday to find an eight-man security team to protect the director-general of the BBC.

“A select group of close protection officers were approached and told that, as a direct result of the Top Gear punch-up and Jeremy Clarkson being sacked by the BBC, the DG had received a death threat. Some of the operation was visible, as a deterrent, while other bodyguards would have kept a very low profile.”

Without naming Hall, the police issued a statement saying they were investigating death threats made last week. “Police in Westminster are investigating an allegation of threats to kill. The allegation was reported to police on Wednesday 25 March,” the statement said.

It is understood that Hall and his wife, Cynthia, have been under guard at their Oxfordshire home after an email was sent to the BBC hours after he took the decision not to renew Clarkson’s contract.

Hall has received a death threat before. In 1999 when he was head of BBC News, he went into hiding under police protection following a call that said he would be next after the murder of Jill Dando.

On Wednesday Clarkson was told his contract would not be renewed at the end of this month after a BBC investigation found he attacked and verbally abused one of the show’s producers, Oisin Tymon, in an incident that left Tymon with a split lip.

The “fracas” followed the absence of a hot meal after a day’s filming. Tymon, who is not pressing charges against Clarkson, has been subjected to a barrage of abuse on Twitter. One Twitter user said they hoped Tymon “visits the morgue very soon”, and another wrote: “Tony Hall BBC director, I wonder if Oisin’s and your head can stop a bullet!!! just wondering.”

Hall said the BBC would look to renew the show for next year and explore ways to screen the remaining episodes of the current series, cut short following the incident that cost the Clarkson his job.

As speculation continued as to who might succeed the immensely popular – if irascible – Clarkson, Chris Evans, the BBC Radio 2 DJ, again ruled himself out of the running.

The bookmakers’ favourite, Evans said dropping Clarkson as host of Top Gear was not a “fatal blow” for the show. He dismissed rumours that co-hosts James May and Richard Hammond were also considering their positions, and backed the pair to keep the series going.

Writing in the Mail on Sunday, Evans said: “In no way does Top Gear need to be reinvented. This series was shaping up to be the best yet. After surviving the insanity of what happened in Argentina for the Christmas special, it felt like the whole team had been drawn closer together as a result.

“As for Jeremy no longer being on the show: sure it’s a huge loss. Top Gear was the show he was born to do. But by no means is it a fatal blow.”

Politics, music and football had survived the departures of Winston Churchill, John Lennon and George Best respectively, Evans said.

Reiterating that he would not be taking over as Top Gear host, the One Show presenter said: “I love Top Gear. But I never want to watch me on it. Of course, I’m flattered that others seem to think my involvement would be a good idea. But they’re hugely misguided.

“I also happen to think I actually wouldn’t be very good at it.”