Singer Cesaria Evora, dubbed the "Barefoot Diva" for often performing without shoes, has died in her native Cape Verde at the age of 70. The musican, forced to retire earlier this year due to ill-health, began her career singing in the bars of Mindelo in the West African island nation. Evora did not begin her recording career until 1988, and won a Grammy Award in 2004 for her album Voz D'Amor. She was famed for singing songs of longing with her rich contralto vocals. Her sultry voice was often compared to blues star Billie Holliday Her fourth album, Miss Perfumado, was her breakthrough hit in 1992. It sold more than 300,000 copies worldwide, and resulted in a number of tours. She released 10 albums in all. Evora had a penchant for alcohol and cigarettes, and in later life her health began to decline. She suffered a stroke while on tour in Australia in 2008 and later underwent open heart surgery. In September, she spoke of her sadness at having to retire, saying: "I have no strength, no energy. I want you to say to my fans: forgive me, but now I need to rest. "I infinitely regret having to stop because of illness, I would have wanted to give more pleasure to those who have followed me for so long." Evora was considered one of the world's greatest exponents of Morna, a form of blues considered the national music of the Cape Verde islands, a former Portuguese colony which gained independence in 1975. The music is a testament to the country's history, including the slave trade and its physical remoteness in the Atlantic Ocean, hundreds of kilometres off Africa's west coast. Two days of national mourning has been declared in the small island nation, with President Jorge Carlos Fonseca calling her "one of the major cultural references of Cape Verde". Prime Minister Jose Maria Neves paid tribute to her "invaluable contribution to the greatness of our nation and our pride".