U.N. Human Rights Commissioner Mary Robinson says she is stepping down as head of the commission when her term ends in September. Mrs. Robinson announced her intentions Monday, at the opening of the annual meeting of the 53-member U.N. Human Rights Commission.

It is believed that major powers like the United States and Russia opposed extending Mrs. Robinson's mandate. She has been a critic of Russia's military campaign against Muslim separatists in Chechnya and of U.S. treatment of Afghanistan prisoners held at the U.S. base at Guantanamo Bay, Cuba.

Mrs. Robinson had already extended her initial four-year term for a year in 2001.

In her speech to the opening meeting of the Human Rights Commission, Mrs. Robinson called for the group to defend human-rights standards now threatened by terrorism. "It is incredibly important that we recognize how valuable the work of 50 years has been in the building blocks of the international framework and the norms and standards of how those who are arrested and detained are treated," she said, "[and in] how the Covenant on Civil and Political Rights in particular is fully adhered to by those countries that have ratified the covenant, how the Geneva Conventions should be applied in times of stress."

For the first time in the commission's 56-year history, the United States is attending only as an observer. It failed to win re-election to the commission last year.

Diplomats say that with the U.S. absence, no other commission member is expected to seek action against China for what critics call its repression of groups like Buddhists in Tibet and the Falun Gong.

Members of the Free Tibet Movement protested outside the Human Rights Commission meeting, praying for their spiritual leader, the Dalai Lama. A spokesman for the group, Jampa Tsering, said he hopes the commission will scrutinize China's human rights record. "Sooner or later the situation of Tibet will change," he said. "The situation itself in China is also, we are thinking, it brings changes for the situation of Tibet. That is what we are expecting and what we are hoping and even we are looking to that point."

During the next six weeks, the commission will examine the human rights situation in the Mideast conflict, Chechnya and Columbia, and it will consider a variety of other issues, including torture and disappearances