Nicole Kidman said her own experience of adopting children led her to her latest role, playing an Australian mother who adopts an Indian child in "Lion," which made its London Film Festival premiere on Wednesday.

"Lion," which opens in US theaters on Nov. 25, follows the true story of Saroo Brierley, played by British actor Dev Patel, who was separated from his family in central India aged 5 when he accidentally boarded a train to Calcutta.

As a lost child unable to remember where his home is, Saroo is put up for adoption and taken in by an Australian couple.

Years later as a grown man living a successful life in Australia, Saroo tries to find his family using satellite images from Google Earth and confronts new challenges as his past life collides with his present.

Australian actress Kidman, 49, who adopted two children with her ex-husband, actor Tom Cruise, said that was the reason she was drawn to play Sue Brierley, Saroo's adopted mother.

"I was drawn to her and she wanted me to play her, which I loved," Kidman said.

"I still wanted every moment that was on screen to be full of her story and her truth ... and that's almost harder than being the lead because it's trying to put all of those complicated emotions and ideas into small scenes," she added.

Patel praised Kidman's performance, saying "her performances come from a very authentic place and to share the screen with her really was a blessing."

The 26-year-old London actor said he spent eight months preparing for the role and learning the Australian accent.

"I started off a bit Crocodile Dundee I think and then I had to be reigned in," he quipped.