The Crown star Helena Bonham Carter has said the show has a "moral responsibility" to make it clear to viewers it is a drama and not historical fact.
Netflix's regal drama has attracted criticism for its use of creative licence.
Oliver Dowden, the Culture Secretary, is expected to write to the US streaming giant this week raising concerns that some viewers may mistake The Crown as a work of fact.
Bonham Carter, who plays Princess Margaret in the show, has discussed the differences between "our version" and the "real version".
"I do feel very strongly because I think we have a moral responsibility to say, 'Hang on guys, this is not... it's not drama doc, we're making a drama,’” she said.
"So they are two different entities,” she said in an interview recorded for The Crown's official podcast after filming on season four finished earlier this year.
Earl Spencer, the brother of Diana, Princess of Wales, has called for Netflix to add a disclaimer making it clear The Crown is a work of fiction.
He told ITV's Lorraine: "I think it would help The Crown an enormous amount if, at the beginning of each episode, it stated that, 'This isn't true but it is based around some real events'.
"I worry people do think that this is gospel and that's unfair."
Peter Morgan, who created The Crown, had previously appeared on the podcast to defend his right to creative licence.
Season four of The Crown explores the Prince of Wales's relationship with Diana. Actress Emma Corrin has won plaudits for her portrayal of the princess.
Former royal butler Paul Burrell said the new season is a "fair and accurate dramatisation" of the royal family's treatment of Diana.
