Speaking to reporters at the State Department, Rice said the announcement from Tehran was further proof it was not adhering to requirements already set out by the international community.

"I do think that the Security Council will need to take into consideration this move by Iran and that it will be time when it reconvenes on this case for strong steps to make certain that we maintain the credibility of the international community on this issue," Rice said.

The UN. Security Council has demanded Iran shelve enrichment activity and on March 29 asked the International Atomic Energy Agency to report on its compliance in 30 days.

Iranian nuclear chief Gholam Reza Aghazadeh announced on Tuesday that Iran had successfully produced 3.5 percent enriched uranium. The success in producing low-grade enriched uranium would pave the way for Iran to start industrial-scale production, he said.