The signing on Thursday at a meeting of the 35-nation board of governors of the International Atomic Energy Agency (IAEA) ends months of haggling over Saudi Arabia signing a Small Quantities Protocol (SQP), an arrangement in effect since 1971 to reduce inspections in nations with small nuclear programmes.
Saudi Arabia, a key state in the Middle East, is not believed to be a direct nuclear proliferation threat, but diplomats were seeking to calm fears amid a major test of wills with nearby Iran, which US officials suspect of seeking to develop nuclear weapons.
There have also been reports - denied by the Saudis - that in a crisis they could use their financial clout to get nuclear technology, or even weapons, from countries such as Pakistan, which does have nuclear arms.
The SQP allows states to be exempted from requirements to notify the IAEA of stocks of natural uranium of up to 10 tonnes.
This "small" amount is still enough to make enough enriched uranium to produce at least one atom bomb.
Weakness of system
IAEA chief Mohamed El Baradei had said on Tuesday that the SQP had now been identified "as a weakness of the safeguards system" of agency inspections.
The IAEA board was debating on Thursday the possibility of rescinding the SQP, in effect since 1971 and signed by 86 countries. But no action was expected to be taken at this board meeting.
US representative George Glass told the board that Washington excused itself for any misunderstanding there had been as it had no intention to single out Saudi Arabia and was disappointed about press reports implying this, a diplomat who attended the closed-door meeting said.
"They [Saudis] are doing what they're asked to do. They don't have much more leeway to give"
Unnamed western diplomat speaking to AFP
A Western diplomat said the controversy about the SQP had been "philosophical and not related to any concerns about the Saudi programme".
Saudi Arabia has signed the nuclear Non-Proliferation Treaty (NPT) that mandates IAEA safeguard inspections but had resisted signing a safeguards agreement.
Egyptian ambassador Ramzy Ezzeldin Ramzy said: "I wish countries would be as enthusiastic about requiring the Israelis to sign the NPT as they are about getting more (inspections) from the Saudis."
El Baradei says SQP is a
weakness to be addressed
Israel, which is believed to have about 200 atomic bombs, refuses to sign the NPT.
Saudi Arabia last weekend turned down a European Union request, backed by similar entreaties from the United States and Australia, to allow full IAEA inspections.
Riyadh said it would agree to this only if other countries exempted under the SQP did the same, EU diplomats said.
Saudi Arabia said this week in a letter to El Baradei that "there are no nuclear materials in installations in the kingdom as defined in the safeguards," according to a diplomat who read the text to AFP.
The diplomat said Saudi Arabia had only a cyclotron for making radioactive isotopes for medical use.
The diplomat said the Saudis were clearly trying to "be a good guy" internationally, as shown in their holding municipal elections recently in an effort to promote democracy.
"They're doing what they're asked to do" the diplomat said about Saudi willingness to sign the SQP, which functions as a safeguards agreement.
"They don't have much more leeway to give," the diplomat added.