Keith Urban penned an adorable message to wife Nicole Kidman as they celebrated their wedding anniversary, saying she still felt like his girlfriend.

The US country star, 49, and the Hollywood actress, 50, tied the knot in 2006.

To mark their anniversary, Urban posted a collage of pictures of the couple on Twitter.

The snaps showed the pair smiling with their arms around each other, and in one Urban was kissing Kidman on the cheek.

He wrote: “Happy Anniversary Babygirl.

“Eleven years and you still feel like my girlfriend!!! – KU.”

Urban and Kidman have two daughters together.