Demi Moore believes an alien encounter "definitely happened" in her hometown.

The Substance actress was born and raised in Roswell - the New Mexico town most famous for the 1947 Roswell Incident, which saw the recovery of debris from a crashed military balloon that led to conspiracy theories it was from an extraterrestrial spacecraft - and always felt "secret" happenings were deliberately not spoken about until it became the focus of documentaries and the TV show Roswell.

Appearing on The Late Show With Stephen Colbert, Demi said: "I just heard of your fascination with aliens, of which my children often have said that they think I'm part alien."

Asked by Stephen why Rumer, 37, Scout, 34, and 31-year-old Tallulah - Demi's daughters with ex-husband Bruce Willis - thought that, she said: "I don't know. Maybe it's just because I was born in Roswell."

The host then quizzed Demi as to whether the citizens of Roswell talked about the alleged UFO crash and she said: "Something definitely happened. But when I was a kid, it was never spoken about. Never. It just was not ever ever talked about, not even in passing. It was as if it was a secret."

"And then when the documentary came out and then the show, now there was a museum, and now there's actually a somewhat comprehensive museum discussing how they shut all communication down about it."

Stephen continued to press the 63-year-old actress as to what she thought had happened and she said: "Well, you know, it's the largest landing strip in America is in Roswell. Outside, so there's a lot of testing that goes on."

And when the host joked she probably couldn't say more without getting into trouble, she laughed and said: "It's possible. I don't want to be seen as illegal."

Demi then told how she is set to star in Strange Arrivals with Colman Domingo, which is based on the true story of Betty and Barney Hill's alleged alien abduction.

Stephen laughed and said: "They're not with us anymore, right? You know why? They talked about it."