LONDON (Reuters) - U.S. singer Anastacia has been diagnosed with breast cancer having successfully battled the disease in 2003, she said in a statement posted on her Facebook page.

The 44-year-old, who had major success outside the United States with hits like the 2000 dance favorite "I'm Outta Love", has been forced to cancel plans to tour Europe starting in London on April 6.

"I feel so awful to be letting down all my amazing fans who were looking forward to 'It's A Man's World Tour'," she said in a statement. "It just breaks my heart to disappoint them," she said.

She added that she will continue writing and recording her new album and hopes to schedule a new tour as soon as possible.

(Reporting by Mike Collett-White, editing by Paul Casciato)