Test-ban treaty countries at the United Nations Thursday urged more nuclear states to end testing, which they say would be an important step toward disarmament and non-proliferation.

In a joint-ministerial statement, 42 foreign ministers bid nations that have not yet signed or ratified the Comprehensive Nuclear Test Ban Treaty to do so without delay.

The CTBT cannot take effect until 12 key states sign on, including the United States, Iran, China, North Korea, Israel, India and Pakistan. At the time of the treaty's adoption in 1996, the commitment of these nations was judged essential because they all possessed nuclear power or research reactors. If it comes into effect, the CTBT would ban nuclear test explosions anywhere in the world, halting nuclear proliferation.

The treaty has 172 signatories and 116 ratifications. Bosnia and Herzegovina, participating in the United Nations' four-day treaty signing event, is expected to sign the CTBT on Friday.

There is, I think, an obvious linkage between the CTBT and nuclear weapons proliferation and other security risks, said Finland's Foreign Minister Errki Toumioj, citing as a major concern the possibility that such weapons may fall into the hands of terrorists.

According to information released Thursday by the International Atomic Energy Agency, the United Nations' atomic watchdog group, terrorists may already possess nuclear material. The agency said that 60 potentially illicit trafficking incidents have been reported since the beginning of this year alone. These incidents include potential cases of unauthorized acquisition and transfer of nuclear and other radioactive materials.

Each case has been registered in the agency's Illicit Trafficking Database, established in 1995 in response to increasing reports of criminal dealings with radioactive material. The database consists of intelligence gathered by 80 participating nations about trafficking of nuclear materiel.

In addition to the 60 state-confirmed trafficking cases, there are some 540 other unconfirmed cases that have been reported in the past decade.

Clearly, the circumstances that first led to a plan for protection against nuclear and radiological terrorism have not diminished, said IAEA Director-General Mohamed ElBaradei in a recent report to the agency's board of governors.

There is a very strong feeling among countries in the world that the threat of nuclear weapons and proliferation has not been adequately met, said Toumioj. All the governments that have signed on to the statement today are working in their bilateral relations and jointly toward getting those who have still yet to sign and ratify the treaty to do so as soon as possible, he said.

Efforts to rid the world of nuclear weapons gained momentum in 1963 with the Partial Test Ban Treaty which prohibited testing in the atmosphere, underwater and in space. The 1968 Nuclear Non-proliferation Treaty was aimed at preventing non-nuclear nations from acquiring or manufacturing such weapons.

The CTBT differs because it bans all nuclear test explosions, even non-military, including those underground. The comprehensive nature of the testing ban would prevent the development of new nuclear weapons or weapons improvement.

If the CTBT takes effect, every nation that has ratified the treaty will have to open its borders to scientists whenever it is suspected of hosting a nuclear test explosion. And with the creation of what Wolfgang Hoffmann, executive secretary of Comprehensive Nuclear Test Ban Treaty Organization, calls the global verification regime, explosions would not go unnoticed.

The verification process, which the organization has been developing since the treaty first opened for signatures eight years ago, consists of an International Monitoring System, a consultation and clarification process, on-site inspections and confidence-building measures.

Of the 337 IMS facilities mandated by the treaty, 190 are close to being ready, Hoffmann said. The monitoring system uses seismic, hydro-acoustic, infrasound and radionuclide technologies to detect evidence of possible nuclear test explosions.

For now, these facilities will go unused while nations supportive of the CTBT use their diplomatic sway to persuade nations to embrace the treaty. We have had some successes as the number of ratifications continues to grow, Toumioj said. But we still have a lot of work to do.