United Nations Secretary-General Kofi Annan warned yesterday the treaty aimed at preventing the spread of nuclear weapons faces serious challenges and must be strengthened to allow unannounced and unrestricted inspections of nations' nuclear facilities.
He said the five-year review conference of the Nuclear Nonproliferation Treaty in May "will test the commitment of all states to nuclear disarmament, nonproliferation and the peaceful use of nuclear energy."
In a speech to the UN Advisory Board on Disarmament Matters, Mr Annan expressed concern at the prospect of terrorist groups' developing or acquiring nuclear, chemical or biological weapons and the means to deliver them.
He also stressed the need to find ways to prevent nuclear technology from being diverted to secret and illegal weapons programs.
The Nonproliferation Treaty (NPT) - the cornerstone of global efforts to control the spread of nuclear weapons - went into effect in 1970 and has been signed by 188 countries, though North Korea withdrew in 2003.
Three countries have refused to join - India and Pakistan, which conducted rival nuclear tests in 1998; and Israel, which is believed to have nuclear weapons.
Last year, UN nuclear chief Mohamed El-Baradei said a truly successful global regime must include all countries.
Mr ElBaradei also lamented that seven years after an additional protocol was adopted allowing intrusive inspections, more than 100 countries still have not signed.
Mr Annan gave his backing to adoption of the additional protocol, calling it "the norm for verifying compliance with the NPT," stressing the importance of the need "to raise the bar for inspection standards."