Urban and Kidman have kept their romance out of the spotlight

The pair have been the subject of speculation for months after Kidman was spotted wearing what appeared to be an engagement ring.

Kidman also told People magazine: "He's actually my fiance."

Confirmation of the engagement ends months of speculation about the couple, both of whom are 38 and were brought up in Australia.

'Major shock'

Urban's representative Paul Freundlich confirmed the engagement to Reuters press agency, but said he had no further details on future wedding plans.

The pair met in January 2005 at an awards dinner in Los Angeles, hosted in their honour by the Australian government.

Kidman was married to actor Tom Cruise for 10 years, with whom she adopted two children.

The Oscar-winning actress recently said that their divorce in 2001 came as a "major shock" to her as she had not been expecting it to happen.

She admitted she still felt enormous love for her ex-husband, who is now engaged to Katie Holmes.