The popular sci-fi franchise Star Trek is set to introduce its first transgender and non-binary characters.

The characters are to appear in the third series of Star Trek: Discovery, producers said on Wednesday.

The trans character, Gray, will be played by trans actor Ian Alexander, and likewise, non-binary Adira will be portrayed by Blu del Barrio.

"Star Trek has always made a mission of giving visibility to underrepresented communities," said a producer.

The show's co-runner and executive producer Michelle Paradise added: "It believes in showing people that a future without division on the basis of race, gender, gender identity or sexual orientation is entirely within our reach."

Welcome Blu del Barrio and @ianaIexander to the #StarTrekFamily! They will be playing Adira, Star Trek's first non-binary character, and Gray, Star Trek's first transgender character in #StarTrekDiscovery Season 3. Learn more about Blu in this @glaad Q&A: https://t.co/gd54tVl8p0 pic.twitter.com/WroJ32n7Cp

— Star Trek on CBS All Access (@startrekcbs) September 2, 2020

The programme, which will begin again next month on US TV network CBS, previously featured the first married gay characters in the franchise's history; while Sonequa Martin-Green also became the first Black woman to lead a Star Trek TV series.

In an interview with GLAAD del Barrio said: "When I got the call that I'd been cast as Adira, I hadn't yet told the majority of my friends and family that I was non-binary.

"So when this happened, it felt like the universe saying 'go ahead'."

Anthony Rapp, one of the show's stars, tweeted: "I cannot wait for you all to meet these beautiful souls and wonderful artists. I am so so so proud of them and happy that they are a part of our show".