Nia Vardalos wanted to tackle political themes in 'My Big Fat Greek Wedding 3'.

The 60-year-old actress has written and directed the new romantic comedy, in which she reprises the role of Toula Portokalos, and did not shy away from the topic of immigration.

Nia told Parade magazine: "This is the most political movie I've ever written.

"I said, 'I'm going to write about this in a way that people will understand we are all humans.' And it's unfair that people are forced from their homes, pushed out by famine or war or loss of income, and pushed into a society that is not necessarily welcoming them.

"So I wrote about it in the new movie, interwoven as part of a giant braid of the bigger story. Nobody wants to be preached to, but we're all immigrants, and that's my message. That's the theme of the third movie."

Nia thinks she has plenty of similarities to her alter ego and regards herself as an "outsider" in the world of celebrity.

She said: "I still feel like an outsider in Hollywood. I'll never feel like I fit in.

"I mean, if I've been invited to parties with famous people in the room, I'll think, 'Who cancelled? Why am I here?'

"I think I always write from the outside looking in. Toula is me; I am Toula. I just have better moisturiser now."

John Corbett returns as Toula's husband Ian and Nia thinks he has helped make the franchise a hit.

The 'Connie and Carla' star said: "We've had such a beautiful relationship.

"I love him as a human being, as a co-star and as my movie husband. I'm so grateful he said yes to the first movie. I don't think we'd be successful if it wasn't for John Corbett as Ian."