Top Gear host Jeremy Clarkson has been suspended by the BBC after what it called a "fracas" with a producer.
Sources said he was accused of hitting the producer in an incident last week, and the remaining three episodes of the current series might not be broadcast.
The BBC confirmed one episode - due for broadcast on Sunday - would not be shown, but gave few further details.
Clarkson, 54, has not commented, but has been joking on social media about films that could replace Sunday's show.
He was given what he called his "final warning" last May after claims he used a racist word during filming.
At the time, he said the BBC had told him he would be sacked if he made "one more offensive remark, anywhere, at any time".
In a statement earlier, the BBC said: "Following a fracas with a BBC producer, Jeremy Clarkson has been suspended pending an investigation.
"No one else has been suspended.
"Top Gear will not be broadcast this Sunday.
"The BBC will be making no further comment at this time."
As thousands of people sign a petition to reinstate Clarkson, he joked around with his fellow presenters Richard Hammond and James May on Twitter.
Referring to the announced cancellation of this weekend's show, May tweeted: "No Top Gear this weekend, apparently. How about 633 Squadron instead? @JeremyClarkson @RichardHammond"
To which Hammond replied:"No, surely, Last of the Summer Wine; no one will notice the difference. Job done. @MrJamesMay @JeremyClarkson"
Clarkson then replied: "No no no. Where Eagles Dare. Much better," before saying: "I did some pretty good war documentaries. They could screen one of those."
Clarkson first started hosting Top Gear in 2002 alongside Richard Hammond and James May.
The hit series faced controversy last year when Clarkson and his co-hosts were hounded out of Argentina by outraging locals.
The controversy began after Clarkson was spotted driving a vehicle with the numberplate 'H982 FKL' - which some people suggested could refer to the Falklands conflict of 1982.
Other Top Gear controversies
May 2014 - The programme drew complaints when video footage leaked to the Daily Mirror appeared to show Jeremy Clarkson using a racist term while reciting the nursery rhyme Eeny, Meeny, Miny, Moe. The presenter later apologised for the incident, which was never broadcast
October 2012 - The BBC Trust ruled comments by Clarkson which likened the design of a camper van to people with facial disfigurements breached disability guidelines.
January 2012 - Indian diplomats complained about a 90-minute India special in which a car fitted with a toilet in its boot is described by Clarkson as "perfect for India because everyone who comes here gets the trots".
February 2011 - The BBC apologised to Mexico after Clarkson and his co-hosts characterised Mexicans as "lazy" and "feckless".
