Nicole Kidman has suggested that she may still have another child - despite being 49 years old - as she revealed that her maternal instinct is her 'strongest drive'.

The actress - who has two children, Faith, six, and Sunday, eight, with husband Keith Urban, and is also mother to Bella, 24, and Connor, 21, who she adopted with ex-husband Tom Cruise - said one of her youngest daughters would like another sibling.

The Australian, who lives in Nashville, said 'one of them wants another one, the other one doesn't'. She added: 'I never say never'.

Maternal instinct: Nicole Kidman, 49, pictured left with two of her daughters and right in New York on Wednesday, says motherhood is her 'strongest drive'

Motherhood: The actress, pictured in her recent film Lion playing an adoptive mom, said her youngest daughters Faith, six, and Sunday, eight, are split on whether to expand the family

Nicole has previously said she has not ruled out adopting more children, but this time appeared to suggest that she could be open to giving birth.

She said there is a precedent for older births in her family after her grandmother had her last child at 49.

When asked whether she has discussed the subject of adoption with her children, she said: 'Yeah because I'm 49 and they're like we'd love a...One of them wants another one, the other one doesn't.'

She added: 'I never say never because the maternal pull is strong. My sister has six children...My grandmother had her last child at 49.

'They said she'd been the oldest woman to give birth in the hospital...At that time that was pretty unusual.'

When it comes to the practicality of potential procreation, Nicole revealed that when she and musician Keith, also 49, want some privacy they tell their daughters it is 'kissy kissy time'.

Driving force: Nicole, who lives in Nashville with husband Keith Urban and their daughters Faith, six, and Sunday, eight, said her 'maternal pull is strong'

Family: Nicole, pictured with Keith and their children, said one of her young daughters wants another sibling, but the other does not

Speaking at screening in New York of her latest film Lion, in which she plays an adoptive parent, on Wednesday, hosted by lifestyle brand The Moms, she said she 'always knew' she wanted to adopt a child.

The film tells the true story of Sue Brierley, an Australian woman who adopted a five-year-old boy, called Saroo, from India. When he grew up he tried to find his birth family.

Like Sue, who Nicole plays in the film, the actress said she 'always knew' she wanted to adopt.

She said: 'I thought, I hoped, that I would have all different ways in which I would be a mother...

'My force, I've realized, in my life is maternal. That's probably my strongest drive.'

She said the pair had such a strong connection when they met to discuss the film that Sue has since become 'one of my dearest friends'.

Topical: The Australian, who is also mother to Bella, 24, and Connor, 21, who she adopted with ex-husband Tom Cruise, plays an adoptive mother in the recent film Lion, pictured

Heartfelt: She said the project, which also stars Sunny Pawar, pictured with Nicole, Dev Patel and Rooney Mara, was 'the most emotional film I've done in a long time'

'That just never happens. She is so maternal and so kind...We have so many similarities and she and I we just clicked.

'So to then play her and all the things she says, that vision, she had that vision, and I had a similar [vision]...I just always knew I was going to adopt. I just always knew,' she added.

Nicole said the project, which also stars Dev Patel and Rooney Mara, was 'the most emotional film I've done in a long time' and that she has had touching responses from audience members - even her own neighbors in Nashville.

'I was walking with my kids two days ago and the neighbors came up and said, they were walking the dog, "we love Lion",' she said.

She wanted to do the project from the moment she first read the script and when director Garth Davis told her that Sue wanted her to play the role she decided that she had to do it.

Poignant: She has had touching responses to the film, directed by Garth Davis, pictured far right with Rooney Mara, Dev Patel and Nicole, including from her own neighbors in Nashville

No option: When director Garth Davis told her that Sue wanted her to play the role she decided that she had to do it

Nicole's eight-year-old co-star Sunny Pawar, who played young Saroo in the film, also appeared at the screening.

Before filming their scenes in Tasmania, Australia, they spent time bonding over sport.

'We played cricket. Me not so good, [he] very good at all sports, soccer and cricket,' Nicole said.

Sunny, who was selected in Mumbai, India, by Garth from a shortlist of more than 100, said his favorite scenes to shoot were the school scenes, the train scene and all of the running sequences.