VIENNA - A clause dropped from a UN resolution on Iran this week calling for "unrestricted access" is now haunting UN inspectors as they investigate Tehran's nuclear program, diplomats and analysts said Thursday.
The problem is that access is often restricted.
Iran is still refusing to give allow inspectors from the UN International Atomic Energy Agency to visit the Parchin military site where there may have been nuclear weapons technology testing, diplomats told AFP.
And UN inspectors have legal restrictions in checking out buildings at a location in Tehran known as Lavizan-II where Iranian resistance spokesmen said secret uranium enrichment was allegedly going on, they said.
A Western diplomat said the UN's International Atomic Energy Agency (IAEA) "can't just go on fishing expeditions. It has to demonstrate some kind of nexus between a facility and nuclear equipment".
In plain English, this means the IAEA has to show reason to believe there is nuclear material at a site before it can check it out.
This is because the IAEA mandate "is to track nuclear equipment and nuclear material," not weapons, the diplomat said.
Thus the IAEA can not check out Lavizan-II in Tehran because it does not yet have the hard nuclear evidence it needs to be allowed a visit, a diplomat close to the IAEA said.
This limited access is spelled out in the Additional Protocol to the nuclear Non-Proliferation Treaty, a protocol which actually was drawn up in 1997 to give IAEA inspectors wider powers.
The powers fall far short of unrestricted access, said David Albright of the Washington think tank the Insitute for Science and International Security.
Albright said South Africa and Libya, two states which have dismantled their nuclear weapons programs, had given the IAEA access even to sites involved in testing or development but where there was no atomic material.
But Iran, which insists its nuclear activities are civilian and peaceful, refuses this, insisting that a resolution adopted Monday at a meeting of the IAEA's 35-nation board of governors in Vienna keep to the terms of the Additional Protocol.
A first version of the British-French-German resolution had called for "unrestricted access to all sites as deemed necessary by the agency."
But the resolution as adopted, in a watered-down form to reward Iran for agreeing to a full freeze of uranium enrichment activities, spoke only of "any access deemed necessary by the agency in accordance with the Additional Protocol."
This leaves the IAEA handicapped in trying to trace possible atomic weapons development.
A diplomat close to the agency said the IAEA's legal authority was "quite limited when you get into the area of nuclear weapons related activity" since actual nuclear material may not be present.
But even when such material is alleged things can move slowly.
The IAEA in October sent a "note outlining modalities" for a visit to Parchin, where Iran's Defense Industries Organization (DIO) does work in explosives, but has still not been allowed to go, diplomats said.
US officials have said the Iranians may be testing in Parchin "high-explosive shaped charges with an inert core of depleted uranium" as a dry test for how a bomb with fissile material would work.
One diplomat said the IAEA "has some nuclear evidence (for Parchin), some reasons to ask, or otherwise it wouldn't ask to go there."
But "the obstacles increase when one is trying to visit a military site," the diplomat said.