The body will be known officially as the UN Entity for Gender Equality and the Empowerment of Women, but officials say it will be referred to as UN Women (www.unwomen.org).

The General Assembly voted in July, after years of difficult negotiations, to set up the entity, which will merge four separate UN divisions now dealing with women's and gender issues.

Bachelet, 58, headed a center-left administration in Chile from 2006 until March of this year, when she was replaced by conservative Sebastian Pinera. Last year, Forbes magazine rated her the 22nd most powerful woman in the world.

Bachelet, who attended two years of high school in the United States, was arrested in Chile in 1975 along with her mother by the rightist military junta that took over the country in a 1973 coup. Exiled to Australia, she later moved to former East Germany before returning in 1979 to Chile where she studied medicine, specializing in pediatrics.

Ban told reporters that 26 candidates had been considered to head the women's entity, but diplomats said Bachelet had been a front-runner from the start.

UN Women will focus on supporting inter-government bodies like the Commission on the Status of Women and ensuring that all UN agencies and organizations live up to their commitments to gender equality, the United Nations says.

UN Women will become fully operational on January 1, 2011.