Nicole Kidman and Keith Urban celebrated their fourth wedding anniversary with a romantic meal.

The couple - who have a 23-month-old daughter, Sunday Rose, together - marked the special occasion last week by dining out at exclusive Nashville restaurant Flyte and onlookers say they couldn't keep their hands off each other during the evening.

One fellow diner told People: "Nicole looked stunning, very understated in a sleeveless dress and sandals. They were smiling and holding hands across the table. You could tell they were so in love."

After their meal, the Oscar-winning actress and the country singer chatted with staff, who described them as a "delight".

Nicole - who has two adopted children, Isabella, 17, and 15-year-old Connor, with ex-husband Tom Cruise - and Keith are happy to publically speak about their love for each other but admit marriage is hard work.

Keith previously said: "The union we've created is something we both want to work on. It is beautiful to be in a union with somebody that is equally loving and passionate, and who wants the best for the other person. We want the best for each other and we support each other to do that. I have never had a situation where I have been willing to do whatever it took to work things out. To find myself in a relationship with a person who is equally willing has been an absolute miracle."