TEHRAN  - Officials from the UN atomic watchdog began a visit to Iran on Sunday to discuss Tehran’s suspect nuclear drive, amid a backlash by furious Iranian lawmakers at a looming EU oil embargo.

The three-day International Atomic Energy Agency mission is to address evidence suggesting Iran’s activities include nuclear weapons research.

The visit was seen as a rare opportunity to maybe alleviate a building international showdown over Iran’s nuclear programme that has seen a ratcheting up of sanctions and talk of possible Israeli military action. “In particular we hope that Iran will engage with us on the possible military dimensions of Iran’s nuclear programme,” Herman Nackaerts, the IAEA’s chief inspector leading the delegation, told reporters in Vienna as he left. “We are looking forward to the start of a dialogue, a dialogue that is overdue since very long,” he said.

Iran’s parliamentary speaker, Ali Larijani, on Sunday called the visit a “test” for the UN agency, according to the website of the official IRIB state broadcaster. If the IAEA officials were “professional” then “the path for cooperation will open up,” Larijani said.

“But if they deviate and become a tool (of the West), then the Islamic republic will be forced to reflect and consider a new framework” for cooperation, he added.

Iran, which maintains its programme is exclusively for peaceful purposes, is increasingly furious at the Western measures aimed at getting it to halt uranium enrichment. It has defiantly stepped up enrichment at a new bomb-proof bunker in Fordo, near the Shia holy city of Qom. It has also reacted fiercely to new sanctions targeting its oil and finance sectors, notably the European Union’s announcement of a ban on all Iranian oil imports within the next five months

Against that backdrop of threat and counter-threat, attention is focused on what the IAEA talks might yield. It was not known, however, whether the delegation would go to any of the sites mentioned in a November IAEA report.

 suggesting Iran had worked on developing nuclear weapons.

The official IRNA news agency reported the mission would go to Fordo, but there was no IAEA confirmation of that.

IAEA chief Yukiya Amano on Friday reiterated his agency had “information that indicates that Iran has engaged in activities relevant to the development of a nuclear explosive device.”

He called on Tehran to show “substantial cooperation”.

Iran has signalled willingness to resume talks with world powers but has yet to reply to a letter sent three months ago by EU foreign policy chief Catherine Ashton offering a return to the talks.

That reply would be forthcoming “soon”, Iranian Foreign Minister Ali Akbar Salehi said, IRNA reported Sunday.

Observers note that, while Iran is feeling the impact of the Western sanctions, it shows no sign of halting its nuclear activities.

“Sanctions have not eliminated Iran’s capacity or desire to continue developing its nuclear programme,” said Dina Esfandiary, analyst with the International Institute for Strategic Studies in London.

“What would be required to affect Iran’s strategic thinking is not tighter unilateral sanctions from the US, EU and other allies, but the implementation of a unified sanctions regime from all Iran’s major trading partners, and that is unlikely to happen,” she said.