But there are precedents, as Western intelligence services were a year and half in the fog regarding a North Korean uranium enrichment plant.

FORBES: Creating Bridges Into North Korea

He accused foreign powers of pushing the UN's nuclear watchdog, the International Atomic Energy Agency (IAEA), to rebuke Iran for covering up another uranium enrichment plant near the town of Qom.

BBC: Iran accuses West of provoking new nuclear sites move

At the Pittsburgh G20 Summit in September 2009, President Barack Obama, then-British Prime Minister Gordon Brown and French President Nicolas Sarkozy exposed a new Iranian underground uranium enrichment plant near Qom.

FORBES: The Dangers Of Doing Business With Iran's Revolutionary Guards

Mr Bush has called for a moratorium on the sale of uranium technologies to countries without them, but he has winked at Brazil's decision to build a uranium-enrichment plant.

ECONOMIST: Diplomacy and proliferation

Iran has told the UN nuclear agency it plans to upgrade uranium enrichment centrifuges at its Natanz plant, reports citing diplomats say.

BBC: Natanz uranium enrichment plant

France, Germany and Britain criticised Iran's decision to start operating a plant for converting uranium into gas before its enrichment in centrifuges.

ECONOMIST: Politics this week | The