The clause is said to prevent the former Top Gear trio from making a similar show for a rival British broadcaster until April 2017.
However, it is thought that online streaming services such a Netflix and Amazon Prime Instant would not be prevented from producing a series with the three presenters.
The trio are thought to have been in talks with ITV after they were seen leaving channel boss Peter Fincham’s house last month.
According to The Mirror, the presenters could still make a show for ITV but it could not be about motoring.
A source told the newspaper: “Basically they could make a show for ITV, but not one about cars. A clause stops them leaving and making a rival.
“It means Netflix or Amazon are favourites to sign up the team...They hope to make up their minds soon. ITV has made them a great offer.”
ITV and the BBC have declined to comment on the speculation.
Last month, Clarkson admitted he has been in talks with US producers, saying he has given up drinking in the evening to help him negotiate better with “Californians”.
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“Californians have a habit of ringing at 11pm and I couldn’t think as straight as they do with their leaves and mineral water existence if I was halfway through my third bottle of Léoube,” he wrote in his Sunday Times column.
Top Gear will return next year with Chris Evans in the driving seat. His two new co-presenters have yet to be confirmed.
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