Angelina Jolie revealed on Tuesday that she has undergone a double mastectomy to reduce her high risk of breast cancer, saying she is speaking out to encourage women address threats to their health.

Jolie, whose mother died of cancer at the age of 56, said she had managed to keep the issue quiet and continue working. Her medical procedures ended late last month. 'But I am writing about it now because I hope that other women can benefit from my experience,' she said.

The 37-year-old American actress wrote in an opinion piece entitled 'My Medical Choice' in The New York Times that she had chosen the procedure because she carries a faulty gene that increases her risk of both breast and ovarian cancer.

Jolie, one of Hollywood's best-known faces and the partner of actor Brad Pitt, said that because of this gene, known as BRCA1, her doctors estimated she had an 87 per cent risk of breast cancer and a 50 per cent risk of ovarian cancer.

'Once I knew that this was my reality, I decided to be proactive and to minimize the risk as much I could. I made a decision to have a preventive double mastectomy,' she wrote.

'I started with the breasts, as my risk of breast cancer is higher than my risk of ovarian cancer, and the surgery is more complex,' Jolie wrote.

She said that on April 27 she completed the three months of medical procedures that the mastectomi.