Nicole Kidman has found herself at the centre of a social media storm after sharing a heartfelt Mother's Day tribute featuring just two of her four children.

The Oscar-winning Australian actress, 58, posted a serene image to Instagram on Sunday showing herself in the desert with daughters Sunday Rose, 17, and Faith Margaret, 14, whom she shares with ex-husband Keith Urban.

In the sweet family snap, Nicole was seen carrying one of her daughters on her back while smiling at the other, with the trio surrounded by stunning red rock scenery.

'My two girls are everything to me,' she captioned the post, alongside a red heart emoji.

While many fans praised the touching tribute, others were quick to criticise the Babygirl star for appearing to overlook her two adopted children, Bella, 32, and Connor, 30, whom she shares with ex-husband Tom Cruise.

The omission sparked fierce debate in the comments section, with some accusing Nicole of disregarding her older children.

'Even if the other two kids chose not to be in my life, I'd still acknowledge them. She can do what she wants, as she chose to. I'd be different but no one knows the actual story,' one person wrote.

'What about the other 2??? C'mon, Nicole… Full stop,' another added.

A third commented: 'Wow that's so sad - I know get why she didn't invite you to her wedding in London. Adopting kids isn't a fashion move it's a lifetime commitment - so upsetting.'

Others appeared confused by the post, with one follower asking: 'I thought you had 4 kids! This is so weird.'

'What about your other 2, just because you don't have a relationship with them doesn't mean you disregard their existence,' another wrote.

'Thought you had 4 kids??' one fan questioned, while another simply added: 'Don't you have a son?'

However, Nicole's supporters rushed to defend her, arguing that her relationship with Bella and Connor has long been private and complicated due to their ties to Scientology.

Nicole adopted Bella and Connor during her marriage to Cruise before the couple split in 2001.

Over the years, speculation has surrounded Nicole's estrangement from her eldest children, though Bella and Connor have largely remained out of the spotlight.

Nicole has previously spoken lovingly about all her children but has often kept discussions about Bella and Connor to a minimum.

The actress now largely focuses her public family life around Keith and their two teenage daughters, who occasionally accompany her to public events.