Spokesman Robert Wood said Saturday that despite improvements from an earlier draft, the changes in the final text do not address US concerns of anti-Israel and anti-Western bias. The administration had lobbied hard for more revisions so that it could participate.
"It now seems certain these remaining concerns will not be addressed in the document to be adopted by the conference next week. Therefore, with regret, the United States will not join the review conference," Wood said.
Anti-Israel sentiment feared
Concern is high that the April 20 to 25 conference in Geneva may descend into heated debate over Israel that marred the last such gathering eight years ago, especially since Iran's hardline president Mahmoud Ahmadinejad - who has called for Israel's destruction - will attend.
The United Nations organized the forum to help heal the wounds from its last such forum, in Durban, South Africa. The United States and Israel walked out of that 2001 conference when Arab states sought to define Zionism as racist.
Associated Press and Reuters contributed to the report