Executives at CBS, which shows Survivor, said that I'm A Celebrity... in which eight minor celebrities braved the Australian outback to raise money for charity, is too similar in format to their show.
They are now tryng to stop plans by US network ABC and UK producers Granada, to bring the show to American screens.
Lawyers for CBS have told both companies that they have until Wednesday to promise, in writing "that they will not broadcast or license in the United States any programming based in whole or part on the Celebrity series."
Action
An ABC spokesman said they were deciding how to respond.
"We just received the letter and we're in discussions with Granada about it and will decide upon a course of action once those discussions are completed," said a spokesman.
CBS have yet to say say what action they might take against ABC and Granada if they proceed with their plans.
The action comes just days after Bob Geldof started legal action against the makers of I'm A Celebrity...Get Me Out Of Here, saying the idea was stolen from his own production company's show Survivor.
Geldof's company, Castaway Television Productions Ltd, which he co-owns with Charlie Parsons and Lord Alli, owns the rights to the reality TV Survivor format.
They are now attempting to sue Granada and London Weekend Television, who produced I'm A Celebrity... for copyright infringement.
The company said: "I'm A Celebrity... Get Me Out Of Here was not made by or with the consent of Castaway, the owner of the worldwide rights in the international hit television series Survivor.
Charities
"Survivor took many years to develop, a process costing hundreds of thousands of pounds."
The show features 16 people stranded in a remote location, competing for a £1m prize.
I'm A Celebrity...Get Me Out Of Here saw the likes of Tony Blackburn, Tara-Palmer Tomkinson, Nigel Benn, Darren Day, Nell McAndrew and Uri Geller stranded in the Australian jungle.
Veteran DJ Blackburn eventually won the show after viewers voted off the other contestants over the course of a fortnight.
The programme raised over £600,000 for various charities.