UNITED NATIONS — UN Secretary-General Ban Ki-moon on Thursday named South African judge Navanethem Pillay as the world body's new human rights chief, despite initial U.S. concerns about her background.

Ms. Pillay, who would succeed outspoken Canadian Louise Arbour, is a judge at the International Criminal Court in The Hague. UN diplomats and officials said the United States initially resisted the idea of appointing her due to concerns about her views on abortion and other issues but eventually agreed to drop its opposition.

UN spokeswoman Michele Montas said UN Secretary-General Ban Ki-moon expected that Ms. Pillay “will preserve the independence of her office and will maintain effective working relations with the General Assembly and the Human Rights Council.”

Ms. Montas said the UN General Assembly would meet on Monday to discuss the confirmation of Ms. Pillay's appointment to one of the highest-profile and most controversial UN jobs. Diplomats and UN officials said a rejection was extremely unlikely.

Ms. Arbour, a Canadian, said in March she would not seek a second four-year term as the Geneva-based UN High Commissioner for Human Rights after her term expired in June.

In an interview with Reuters, U.S. Ambassador to the United Nations Zalmay Khalilzad congratulated Ms. Pillay on her new job.

“It's a very important job,” he told Reuters. “We need a strong voice, we need a credible voice to speak on the issue of human rights issues, one of the key missions of the United Nations and we look forward to working with her.”

Mr. Khalilzad denied that Washington had formally opposed Ms. Pillay, while acknowledging there were allegations about her background the United States had wanted investigated.

“We didn't find substance in the allegations,” he said.

South Africa's UN ambassador, Dumsani Kumalo, also welcomed the appointment, while rejecting what diplomats said was another concern raised by Washington – that Ms. Pillay might be too close to South Africa's government, which has annoyed Washington with its stance on Zimbabwe, Iran and other issues.

“She's never worked for the South African government,” he told reporters. “She's a highly independent lady.”

Diplomats said some human rights groups had expressed concern that Ms. Pillay might not be as outspoken as Ms. Arbour.

Kenneth Roth, executive director of Human Rights Watch, said it was important the Harvard University-educated Ms. Pillay uses the “bully pulpit” as the human rights chief.

“If she resorts to quiet diplomacy, she'll be fighting with one hand tied behind her back,” he said, adding Ms. Pillay would have “to ensure that her office addresses even powerful governments,” including the United States and South Africa.

As a lawyer in South Africa, Ms. Pillay defended anti-apartheid activists and championed the right of Nelson Mandela and other dissidents to legal assistance.

The daughter of a bus driver, Ms. Pillay grew up in a poor Indian neighbourhood in Durban. She was born in 1941 and, as a member of South Africa's Tamil minority, faced discrimination during the apartheid years because of her dark skin.

As a defence lawyer in the early 1970s, she helped expose the use of torture and unlawful methods of interrogation in South Africa. From 1995, she was on the International Criminal Tribunal for Rwanda, eventually becoming its president.

Jo Ann Palchak, a U.S. lawyer and expert on the ICC and Rwanda tribunal, said Ms. Pillay's questioning of a rape victim at the Rwanda tribunal helped push the issue to the forefront of the case, which ended with international law's first genocide conviction.

“From this decision arose a new definition of rape in international law, one that has had significant impact in later tribunal cases,” Ms. Palchak said. “Those most in need of human rights can cheer her selection.”