Caitlyn Jenner doesn't know how 'I'm a Celebrity...Get Me Out of Here!' works.

Caitlyn Jenner

Caitlyn Jenner

The 70-year-old star has signed up for the ITV reality show, but Caitlyn - who is rumoured to be the best-paid contestant on the upcoming series - has admitted she doesn't know what will confront her in the jungle.

She told The Sun Online: "I am not allowed to talk about this until next week. I am not sure what I can say. I am not allowed to say anything."

Then, after being wished well during her time in Australia, Caitlyn added: "Thank you. I don't know how it works."

Meanwhile, the show's bosses are said to be delighted to have Caitlyn on board for the upcoming series.

An insider shared: "She's such a huge name and a great get for producers.

"ITV think she is one of their best ever signings. It's a real bolt from the blue. They've asked her every year for a long time, but she finally felt the time was right."

Caitlyn will reportedly be joined on the show by Radio 1 DJ Adele Roberts, who has - according to The Sun newspaper - become the tenth celebrity to sign up for the series.

Adele, 40, and Caitlyn will both soon head to Australia, where they'll reportedly team up with the likes of Ian Wright, Nadine Coyle, Jacqueline Jossa, Kate Garraway, James Haskell, Roman Kemp and Myles Stephenson.

The new series of 'I'm a Celebrity...Get Me Out of Here!' is set to begin on November 17.