Media playback is unsupported on your device Media caption L'Wren Scott had cancelled a fashion show she was due to attend recently, the BBC's David Willis explains

L'Wren Scott, a designer and the girlfriend of Sir Mick Jagger, has been found dead in her New York City flat.

Scott, 49, was found at 10:00 local time (14:00 GMT) by her assistant.

Police are treating it as a suicide, although the medical examiner has yet to determine an official cause of death.

A spokesman for Sir Mick said the Rolling Stones singer was "completely shocked and devastated" by Scott's death.

The band is currently on tour in Australia.

Scott, born Luann Bambrough, was raised by adoptive parents in the US state of Utah.

She began her career as a model in Paris, then moved to Los Angeles to become a fashion stylist, according to a biography on her company's website.

She and Sir Mick began dating in 2001. She founded her own fashion label in 2006.

Image copyright Getty Images Image caption Scott and Sir Mick had been together for 13 years

Scott's death comes a month after she cancelled a show at London Fashion Week, saying production delays had left key pieces unready for the show.

As news of her death spread, tributes rolled in from around the fashion world.

Fashion website Style.com praised her as "skilled in costume design" and said she was responsible for Sir Mick's performance outfits on the Rolling Stones' current tour.

"Rest in peace, L'Wren Scott. You'll forever be missed," wrote designer Marc Jacobs on Twitter.

Steven Colb, chief executive officer of the Council of Fashion Designers of America, wrote, "So very sad today. L'Wren Scott was such a great talent and beautiful person. My thoughts are with her loved ones."