BBC America is reportedly "furious" with CBS over the US network's plan to produce a modern-day Sherlock Holmes series.
Elementary - devised by Medium writer Rob Doherty - will transport Sir Arthur Conan Doyle's detective to present-day New York.
BBC America chiefs have labelled the project as a "blatant... copy" of UK drama Sherlock, claims The Mirror.
"We want Sherlock to rate big in the States and this could take the shine off it," an unnamed source apparently told the tabloid.
A 'US TV source' added: "The success of Sherlock in the UK has been major factor of bringing Elementary to life. We believe this modern twist will appeal to viewers. We want fresh American faces in the role."
BBC One's Sherlock - co-created by Steven Moffat and Mark Gatiss - has already been commissioned for a third series.
Moffat recently promised that fans will not have "that long" to wait for new episodes.
"We're making movies - those six films we've made could go in the cinema," said the writer. "You can't factory produce that - it's a different kind of show.
"So, when we're good and ready - it won't be that long - but when we're ready, you'll get the follow-up."
The second series of Sherlock concluded on Sunday night, pulling in 7.9m for BBC One.
Wonder what The Moff has to say?
Some are born great, some achieve greatness and some have greatness thrust upon them.
The rest of us are a bit crap.