Nicole Kidman has praised her husband Keith Urban as ''the greatest man in the world''.

The 50-year-old actress tied the knot with the country musician - with whom she has two daughters, Sunday Rose, nine, and Faith Margaret, six - in 2006, and in honour of his 50th birthday on Thursday (26.10.17), she took to social media to pay him a glowing tribute.

On Facebook, alongside a picture of the pair cuddled up together on a bench, the 'Lion' actress wrote: ''Happy birthday to my husband, best friend, lover, baby daddy and the greatest man in the world. We are so lucky that you are ours. Love you from Nicole Mary, Sunday Rose & Faith Margaret xx (sic)''

It comes after Nicole - who also has children Isabella, 24, and Connor, 22, whom she adopted with her former husband Tom Cruise - recently revealed she's ''passionate'' about spending time with her family.

She said: ''My big passion is just my family; my love.

''My daughter said to me, 'You and Daddy kiss all the time.' I thought, 'That's such a fantastic thing for your daughter to say to you.' And that's my passion.

''I know it's a simple answer, but I'm deeply passionate about raising my children and being with my husband.''

And the 'Big Little Lies' star also admitted she takes ''nourishment and energy'' from her husband.

She added: ''To have an 11-year anniversary and still be so much in love as a man and a woman, that is my solace.

''That's where I get so much of my comfort and my nourishment and energy from.''

Meanwhile, Nicole claimed she and her spouse are ''honest'' with their children, and don't shelter them from the tragedies in the world.

She said: ''We keep a very honest conversation between our kids. Our family depends upon an enormous amount of questions and love and support and we're trying to guide a six-year-old and a nine-year-old girl right now into the world.''