British police were on Sunday investigating death threats against BBC director-general Tony Hall following his decision to drop popular "Top Gear" presenter Jeremy Clarkson.
Scotland Yard police headquarters confirmed it was examining allegations made on Wednesday, when Hall confirmed Clarkson`s contract would not be renewed at the end of March after he hit a producer.
"Police in Westminster (central London) are investigating an allegation of threats to kill. The allegation was reported to police on Wednesday," a spokesman said.
"Inquiries continue. No arrests have been made."
The Mail on Sunday newspaper said Hall`s home had been under 24-hour guard since the threat was received.
The weekly tabloid printed pictures showing security outside, claiming it was costing £1,000 ($1,500, 1,350 euros) a day to protect the corporation`s top executive.
A BBC spokeswoman said: "We wouldn`t comment on security matters."
"Top Gear" is the world`s most popular factual television programme, with 350 million viewers per week in 170 countries.
Clarkson, who was the main presenter, is caricatured by fans as a straight-talking man-of-the-people and by detractors as a boorish bigot.
More than a million people have signed a petition calling for Clarkson to be reinstated.
Clarkson`s contract was not renewed after an internal BBC investigation found he physically attacked "Top Gear" producer Oisin Tymon following a lengthy verbal tirade, reportedly because the presenter was annoyed at a lack of hot food after a day`s filming.
The 30-second attack saw Clarkson strike the producer, giving Tymon a swelling, bleeding lip.
The outspoken presenter, 54, flagged the incident to the BBC after Tymon took himself to hospital.
Clarkson`s departure will have financial implications for the British Broadcasting Corporation, as its commercial arm BBC Worldwide earns around £50 million ($75 million, 70 million euros) a year from the show.