The 55 members of the Organisation for Security and Co-operation in Europe (OSCE) will all sign a United Nations convention aimed at stopping nuclear terrorism, France and Russia, which initiated the plan, said on Monday.
Adopted by consensus in April after seven years of negotiations, the convention was added to a series of 12 other anti-terror conventions already in place.
France's ambassador to the OSCE, Yves Doutriaux, said the organisation's 55 members would sign the International Convention for the Suppression of Acts of Nuclear Terrorism in mid-September, when it will be presented for signature by presidents and heads of state starting mid-September at a summit in New York.
The OSCE, which spans the geographical area from Vancouver to Vladivostok, aims at increasing dialogue and co-operation between East and West. The convention will come into force when it has been ratified by 22 states.
Russia initiated the convention in 1997, in what Russian ambassador to the OSCE Alexei Borodavkin said was an attempt to be able to "prosecute and extradite" suspected terrorists believed to hold nuclear materials, notably in part of the former Soviet Union.
Asked about the connection with the Russian breakaway republic of Chechnya, he said "terrorism and Chechnya are interconnected... Nowadays (Russian law enforcement agencies) have the situation under control."
UN Secretary General Kofi Annan made the convention a priority as part of a series of proposals he would like to see the international community adopt before the September summit.
Alyson Bailes, director of the Stockholm International Peace Research Institute said the threat of nuclear terrorism lay not so much in the theft of nuclear weapons as in the use of radioactive waste - from hospitals, for example - to make a "dirty bomb".