Halle Berry has said she believes in aliens - and it could take just a few decades to find them.

The Oscar winner plays a pregnant astronaut in the new CBS sci-fi drama Extant.

The Hollywood actress told David Letterman's chat show that she thinks there must be life on other planets.

"I don't believe we are the only species in existence," The Hollywood Reporter quotes her as saying.

"My ego doesn't tell me that we're the only ones who survived... it might take us 20 years to get to those other life forms, but I think they are out there."

She told the Late Show host that viewers will have to watch at least 12 episodes to discover how her character became pregnant.

In the series, Halle's character finds that she is pregnant despite having just returned from a year alone in space, and g iving nothing away, she joked: "It could be the pool man."

Halle, married to French actor Olivier Martinez, also helped the chat show host present a segment called "Top 10 Secrets To A Happy Marriage".

The list, which includes, "talk a lot", "don't fight out loud", and "you need to kiss", was penned by her six-year-old daughter, Nahla, when a co-star on the set of her new drama, to be shown on Amazon Prime, got married.