U.S. Ambassador Susan Rice said Washington still believed the body was flawed, but added: We are looking forward to working from within with a broad cross-section of member states to strengthen and reform the Human Rights Council.
The United States was one of 18 countries elected or reelected to three-year terms on the 47-seat Geneva-based council in a vote by the U.N. General Assembly, joining 29 others who are in mid-term.
Some nations that have faced criticism for their own human rights records, including China, Cuba and Saudi Arabia, were among those elected on Tuesday.
The council meets three times a year to review global rights issues as well as holding special sessions on crises. It is halfway through scrutinizing the human rights situation in every U.N. member state under a new periodic review mechanism and can appoint experts to probe abuses in specific countries.
But critics say it is dominated by Muslim countries and their allies who focus on Israel's treatment of Palestinians and ignore abuses in influential developing states. The Bush administration took that view and stayed out of the council, set up three years ago to replace a discredited predecessor.
Tuesday's U.S. election was virtually assured under a system in which regional groupings of nations agree in advance on who will stand.
Only three countries vied for the three seats available for the so-called Western European and Others group after New Zealand stepped aside to make way for the United States.
That meant each of those three needed to get only a simple majority, or 97, of the assembly votes. The United States got 167 votes, compared with 179 for Norway and 177 for Belgium.
U.S. 'NOT PERFECT'
The United States often has criticized human rights abuses in other countries but in recent years has come under criticism itself for using interrogation techniques that critics call torture on terrorism suspects.
There will always be some countries whose respect and record on human rights is sub-par. We have not been perfect ourselves, Rice said. But we intend to lead based on the strong, principled vision that the American people have about respecting human rights, supporting democracy.
But the U.S. decision to enter the council divided both politicians and advocacy groups. On Monday, former Czech President Vaclav Havel called the elections a farce.
U.S. Representative Ileana Ros-Lehtinen, a Florida Republican, said U.S. membership would not change the grim reality of the council. It will only legitimize the council's anti-freedom, anti-U.S., anti-Israel actions, she said.
Only two groups -- Africa and Eastern Europe -- had contested elections. In Africa, Kenya failed to get in while Cameroon, Djibouti, Mauritius, Nigeria and Senegal were elected. In Eastern Europe, Azerbaijan lost out at the expense of Russia and Hungary.
Others elected were Bangladesh, China, Jordan, Kyrgyzstan and Saudi Arabia for Asia, and Cuba, Mexico and Uruguay for Latin America.
Hillel Neuer of Geneva-based group UN Watch said the presence of China, Cuba, Russia and Saudi Arabia on the council would result in the foxes guarding the chickens. He said the council's credibility was at stake over its failure to hold an emergency session over the bloody fighting in Sri Lanka.
Steve Crawshaw of New York-based Human Rights Watch welcomed U.S. council membership but criticized its uncontested election. The message that was understood around the world ... (was) that somehow elections without competition make sense, he said.