Angelina Jolie has revealed she has undergone a double mastectomy and reconstructive surgery.

The Oscar-winning actress made the decision to have both breasts removed as a preventative measure after discovering she had an 87 percent chance of developing breast cancer.

Tests revealed Jolie carries the defective gene, BRCA1, which significantly increases her risk of developing ovarian and breast cancer - the disease that killed her mother, Marcheline Bertrand, at the age of 56.

Carriers of the defective gene have, on average, a 65 percent chance of eventually suffering from breast cancer. Following three months of procedures, the chances of the actress developing breast cancer has fallen to five percent.

Jolie, who is also a Special Envoy of the UN High Commissioner for Refugees, says she has gone public is an effort to raise awareness for testing - though she acknowledges many in the US would not be able to afford the test or the treatment..