The call came after the UN's nuclear watchdog said Tehran was stepping up enrichment despite ignoring UN Security Council demands and obstructing inspections.

The US said the report was “a laundry list of Iran's continued defiance of the international community”.

Iran denied hindering the International Atomic Energy Agency (IAEA) and said it would “continue to co-operate”.

In March, the UN Security Council imposed a second round of sanctions on Iran for failing to suspend uranium enrichment, prompting Tehran to limit its co-operation with the IAEA.

However, IAEA inspectors still regularly visit Iran's atomic facilities under the nuclear Non-Proliferation Treaty.

After the IAEA issued its report on May 23, US representative to the UN Zalmay Khalilzad said his government was now considering taking further steps against Tehran.

Head of the IAEA Mohamed ElBaradei has suggested Iran be allowed to keep part of its enrichment programme.

Mr ElBaradei said Iran possessed “the knowledge about how to enrich” and the focus should now be on preventing industrial-scale production.