The office said in a statement that Saint Kitts and Nevis had signed the treaty on Tuesday and that the number of signatories in the Latin America and the Caribbean region "now stands at 27".

But the 1996 test ban treaty had only been ratified as of January by 109 states, the last being Libya that month.

The treaty commits countries which have ratified it to refrain from any kind of nuclear weapons testing.

The treaty appears likely to collapse, however, as all the countries with nuclear capabilities must ratify it in order for it to come into force. The United States has indicated that it has no plans to ratify it.

WAR.WIRE