UNITED NATIONS - UN Secretary-General Ban Ki-moon has called on states to sign and ratify the Comprehensive Nuclear-Test-Ban Treaty (CTBT) in a message to mark the 5th International Day against Nuclear Tests.

"The Comprehensive Nuclear-Test-Ban Treaty is essential for the elimination of nuclear weapons. It is a legally-binding, verifiable means by which to constrain the quantitative and qualitative development of nuclear weapons," the secretary-general said.

"This year marks the 70th anniversary of the dawn of the nuclear age. Seven decades ago, the Trinity Test unleashed the power of more than 20,000 tons of TNT and precipitated over 2,000 additional nuclear tests," he said.

The secretary-general reminded people that "poisoned groundwater, cancer, leukemia, radioactive fallout -- these are among the poisonous legacies of nuclear testing. The best way to honour the victims of past tests is to prevent any in the future."

Nearly two decades after the CTBT was negotiated, the time has long past for its entry-into-force.

Therefore, "I welcome the voluntary moratoria on testing imposed by nuclear-armed States. At the same time, I stress that these cannot substitute for a legally-binding treaty," Ban said.

"On this International Day, I repeat my longstanding call on all remaining States to sign and ratify the Treaty -- especially the eight necessary for its entry-into-force -- as a critical step on the road to a nuclear-weapon-free world," he said.

To date, 183 states have signed and 164 have ratified the treaty. Yet of the 44 specified countries, India, Pakistan, and North Korea still have not signed, and only 36 have ratified the treaty.

The UN General Assembly declared Aug. 29 the International Day against Nuclear Tests in 2009, adopting a unanimous resolution that calls for increasing awareness and education about the effects of nuclear weapon test explosions or any other nuclear explosions and the need for their cessation as one of the means of achieving the goal of a nuclear-weapon-free world."

The year 2010 marked the inaugural commemoration of the International Day against Nuclear Tests.