Kidman has moved into Kravitz' apartment

The actress and musician have "come clean" about their romance after months of rumours that they were dating, People magazine said.

Kidman's spokesman Leslie Dart told the US magazine: "They're very close. He's very important to her."

The report follows Kidman's move into Kravitz's New York apartment.

Kravitz has a teenage daughter

She has repeatedly denied a romance, saying the pair were just good friends. But speculation has mounted over a romantic relationship and even a possible engagement.

The couple have frequently been seen in public together since Kidman moved in with Kravitz while her $8m (�4.8m) New York apartment is renovated.

People quoted eyewitnesses as saying the pair were "flirtatious" during a birthday party last month for Kidman's best friend, fellow Australian actress Naomi Watts.

Kidman's Los Angeles' representatives declined to comment on the report, but denied rumours that the star and the US musician were engaged.

Kidman has two adopted children, Isabella, 10, and Connor, eight.

Kravitz, 39, has a 14-year-old daughter with former wife Lisa Bonet, one of the stars of TV's The Cosby Show.

Kidman, who won the 2003 best actress Oscar for The Hours, has been working non-stop since her high-profile 10-year marriage to Cruise collapsed in 2001.