The United States is likely to sit out next week's UN conference on racism or take part only as an observer, diplomatic sources said yesterday.

The UN organised the forum to help heal the wounds from its last such forum, in Durban, South Africa. The US and Israel walked out of that 2001 conference when Arab states sought to define Zionism as racist.

The Obama administration has largely kept its distance from preparations for the 'Durban II' meeting, that opens tomorrow at the UN's European headquarters in Geneva.

Israel and Canada will not attend because they fear a repeat of the "Israel-bashing" at the last conference.

Juliette de Rivero of Human Rights Watch said that without Washington there, the meeting could lack diplomatic gravitas.

"For us, it's extremely disappointing and it's a missed opportunity, really, for the United States," she said of its expected absence.

"If the US fails to participate, it will disappoint many who invested hope in the Obama administration's commitment to engage internationally to protect human rights."

Several EU members also share US reservations about the possibility that the conference, which Iranian President Mahmoud Ahmadinejad will address tomorrow, will be dominated by criticism of Israel.