The action is seen as a response to toughening western sanctions. Iran has said it is forced to manufacture nuclear fuel rods, which provide fuel for reactors, on its own since international sanctions ban it from buying them on foreign markets.
Iran argues that the EU oil embargo will not cripple its economy, claiming that the country already has identified new customers to replace the loss in European sales that account for about 18 percent of Iran's exports.
An Iranian news agency said Wednesday that the country also has started using new advanced centrifuges at its main uranium enrichment site.
This news comes as a third Iranian suspect, accused of making bombs that exploded in a house in Bangkok, was caught after escaping to Malaysia. The explosion blew off the roof of the house.
Israel said the arrests, combined with attacks elsewhere against its diplomats, are evidence of covert Iranian plots.
The Associated Press contributed to this report.