BBC Worldwide and Italo pubcaster RAI are suing Italian broadcast group Mediaset, reality giant Endemol and Mexican conglom Televisa for copyright infringement in Italy, claiming that Mediaset’s “Baila!” is an illegal copy of the BBC’s “Dancing With the Stars” format.

Baila!,” adapted from Televisa’s popular Latin American format “Bailando por un sueno” (Dancing for a Dream), is due to debut on Mediaset’s flagship Canale 5 on Sept. 27.

RAI’s “Dancing With the Stars” adaptation, “Ballando sotto le stelle,” has been reaping stellar ratings in Italy since 2005.

Mediaset said in a statement that Endemol, from which it purchased the “Baila!” format, has guaranteed that it’s original. It rejected accusations of plagiarism, quoting Mediaset VP Pier Silvio Berlusconi as saying that a key difference between the two shows is that “Baila!” has “both celebrities and normal people,” unlike “Dancing With the Stars.”

The same Endemol format is the basis for “Mira quien baila,” the dance show that’s a hit with Hispanic auds on Univision in the U.S. But the BBC and RAI claim that “Baila!” would certainly violate Italian copyright law.

BBC Worldwide takes the protection of its copyright extremely seriously and is currently undertaking legal action in Italy to protect its format,” the BBC said in a statement.

Dancing With the Stars’ has been named the world’s most successful reality TV format and has been licensed to more than 35 broadcasters. It is very important to BBC Worldwide and its international licensees that the format is protected from infringement.”

A decision by a Rome court is expected in coming days.

(Steve Clarke in London contributed to this report.)