VIENNA/TEHRAN, 19 November 2005 — The UN nuclear watchdog said in a confidential report yesterday Iran had given it a document which diplomats said included partial instructions for making the core of a nuclear bomb.

The US ambassador to the International Atomic Energy Agency (IAEA) said the disclosure raised concerns about weaponization but other diplomats and a US nuclear expert were more cautious, saying more investigation was needed into the issue.

“Iran’s full transparency is indispensable and overdue,” said IAEA chief Mohamed El-Baradei in a confidential report to the agency’s board of governors.

The report, seen by Reuters, said that among other documents it had found one “on the casting and machining of enriched, natural and depleted uranium into hemispherical forms”. One European diplomat described it as a “cookbook” for the enriched uranium core of a nuclear weapon.

But a US nuclear expert, David Albright of the Institute for Science and International security, said it was far from a step-by-step guide to producing a bomb core.

“Iran has gone from saying it got nothing on this subject to (saying it got) a little bit,” he said. “But the question remains: Did Iran get more than it admitted to?”

The Iranians told the IAEA the document had come to them unsolicited from people linked to the nuclear black market set up by Pakistani nuclear scientist Abdul Qadeer Khan.

While Iran had been “more forthcoming” in providing access to documents and information in some areas, questions on the peaceful nature of its nuclear plans remained, the report said. The IAEA report asked Iran to provide information on dual-use equipment and allow visits to sites such as those at Lavizan. Washington says one site was used for sensitive nuclear work but was bulldozed before IAEA inspectors could visit it. Iran’s chief nuclear negotiator Ali Larijani said earlier the IAEA should justify its request for access to Lavizan.

“We cannot accept this demand just because they wish it, especially since Lavizan-Shian is a military complex,” the semi-official ISNA students’ news agency quoted him as saying. Larijani also confirmed Iran had resumed uranium conversion at its Isfahan plant. “We had informed the UN watchdog that Iran wanted to process a new batch of uranium and we have started it,” he told reporters on Thursday. Iran, which hid uranium enrichment activities from the IAEA for 18 years until 2003, told the Vienna-based body last month it planned to process a new batch of uranium.

Larijani did not say when processing had resumed at Isfahan, but diplomats in Vienna reported it on Wednesday. France said this Iranian move did not help foster confidence. “We consider that this is a decision which does not go in the right direction,” a Foreign Ministry spokesman said in Paris.