The Comprehensive Nuclear Test Ban Treaty opened for signatures 12 years ago. Since then, 179 nations have signed and 144 ratified it. Missing are nine states with nuclear activities, whose ratification is required.

'The (treaty) has achieved near universal adherence,' Mr Ban told a meeting of 40 foreign ministers on the sidelines of the UN General Assembly. The ministers issued a statement appealing to holdout countries to ratify the pact.

'Despite the progress that has been made, the CTBT has still not entered into force,' Mr Ban said. 'This is cause for serious concern.'

Echoing the ministers, he urged 'all governments that have not yet done so to sign and ratify the treaty without delay.'

The United States signed the treaty in 1996 during the administration of President Bill Clinton, a Democrat, but a Republican-majority US Senate rejected it 1999.

When President George W. Bush took office in 2001 his administration made clear it did not want its options limited by such a treaty and never resubmitted it.

'The United States has not conducted a nuclear test since 1992 and continues to observe its nuclear testing moratorium,' the US mission to the United Nations said in a statement.

Next president
Mr William Perry, the US defence secretary when Washington signed the treaty, said he thought the next president, whether Republican Sen John McCain or Democratic Sen Barack Obama, will send it back to the Senate for ratification.

'I believe that has a good probability of changing with the new president of the United States,' Mr Perry said.

Washington is joined by China, North Korea, Egypt, India, Indonesia, Iran, Israel and Pakistan as holdout countries whose ratification is necessary for the treaty to enter into force.

Some analysts have said that if the United States fails to ratify the treaty, it will most likely die.

China, Israel, Pakistan and India are also considered nuclear weapon states. Western countries believe Iran has a secret atom bomb programme but Teheran denies this.

North Korea, which conducted a nuclear test in 2006 and agreed last year to scrap its atomic weapons programme in an aid-for-disarmament deal, has expelled UN monitors from a plutonium-producing that it plans to reactivate next week.

Australian Foreign Minister Stephen Smith said North Korea's recent moves were alarming and expressed the hope that the UN Security Council would consider 'further diplomatic measures' to pressure Pyongyang to change course.

German Foreign Minister Frank-Walter Steinmeier urged India, which hopes to develop normal nuclear trade relations with the world's top producers and suppliers of atomic technology, to sign the pact. Like Israel and Pakistan, India has not signed the nuclear Non-Proliferation Treaty aimed at stopping the spread of atomic weapons. -- REUTERS