UN Secretary-General Kofi Annan speaks during a conference to review the Nuclear Nonproliferation Treaty

A conference on nuclear non-proliferation has opened at the United Nations amid concerns about the nuclear intentions of Iran and North Korea.

Representatives of more than 180 countries sat down in the General Assembly Hall for a five-year review of the treaty that is considered the legal cornerstone of international efforts to control the spread of nuclear weapons.

Secretary-General Kofi Annan opened the gathering with a frank admission that the 35-year old treaty is out of date. He suggested that success of the month-long conference is in danger because of vastly differing expectations.

"Some will stress the need to prevent proliferation to the most volatile regions," said Mr. Annan. "Others will argue that we must make compliance with, and enforcement of, the NPT universal. Some will say the spread of nuclear-fuel cycle technology poses an unacceptable proliferation threat.

"Others will counter that access to peaceful uses of nuclear technology must not be compromised," continued Mr. Annan. "Some will paint proliferation as a grave threat. Others will argue that existing nuclear arsenals are a deadly danger."

Without mentioning any state, the secretary-general made clear his concerns about North Korea, suggesting that Pyongyang's withdrawal from the treaty poses a grave challenge to its credibility.

"You must strengthen confidence in the integrity of the treaty, particularly in the face of the first withdrawal announced by a state," added Mr. Annan. "Unless violations are directly addressed, the most basic collective reassurance on which the treaty rests will be called into serious question."

Mr. Annan also indirectly rebuffed Iran, which many suspect is using its quest for peaceful nuclear energy as a cover for a weapons program.

"States that wish to exercise their undoubted right to develop and use nuclear energy for peaceful purposes must not insist that they can only do so by developing capacities that might be used to create nuclear weapons," he said.

Mr. Annan also avoided mentioning the United States and Russia, but did make a pointed reference to demands by several countries that former Cold War advsersaries have been too slow to disarm.

"An important step would be for former Cold War rivals to commit themselves irreversibly to further cuts in their arsenals, so that warheads number in the hundreds, not the thousands," he reminded.

Undersecretary of State Stephen Rademaker is among 17 delegates scheduled to address the conference later on its first day. Mr. Rademaker has previously said that while the United States has no plans to introduce new disarmament initiatives during the conference, it will seek to hold NPT violators accountable.

The United States is also seeking political support for a proposal to require nuclear-capable states to refuse to supply enrichment and reprocessing technology to states that do not have functioning nuclear-energy plants.