The US has described Iran’s enrichment of uranium underground as a “further escalation” of its violation of UN resolutions.

Iran has now begun enriching uranium underground up to 20 per cent in a mountain in Fordow, close to the city of Qom. Centrifuges and other equipment necessary for enrichment were installed at Fordow in 2011 (MEED 8:1:12).

On 9 January, the UN’s Vienna-based nuclear watchdog, the International Atomic Energy Agency (IAEA) confirmed that Tehran has started enriching uranium at the Fordow plant. Tehran maintains the 20 per cent-enriched uranium is needed for a research reactor to make isotopes to treat cancers. Western powers have called on Iran to suspend enrichment activities immediately.

“We call on Iran once again to suspend enrichment activities, cooperate fully with the IAEA and immediately comply with all UN Security Council and IAEA board of governors resolutions,” US state department spokeswoman Victoria Nuland said in a statement.

The French foreign ministry says that Iran’s uranium enrichment in Fordow “leaves us with no other choice but to reinforce international sanctions and to adopt, with our European partners and all willing countries, measures of an intensity and severity without precedent.”

British Foreign Secretary William Hague called Tehran’s move a “provocative act which further undermines Iran’s claims that its programme is entirely civilian in nature.”

The IAEA says that all nuclear activity in the Fordow facility remains under the agency’s containment and surveillance. Iranian Supreme Leader Ayatollah Ali Khamenei says the “Islamic establishment…knows firmly what it is doing and has chosen its path and will stay the course.”

Relations between Iran and the West have been strained since the US imposed further sanctions on Iran’s central bank in November 2011. The EU is due to meet later this month to approve an embargo planned on Iran’s oil exports. Iran has threatened to close the Strait of Hormuz, if the embargo goes ahead. About 20 per cent of the world’s traded oil passes through the strait.