For the same reason, Americans employed by the company are prohibited from taking part in the Iranian activities, the spokesman said.

Iranian activity dropped off after the certificates were revoked.

"Since the end of the war, we have seen an increase in Iranian activity in the region," said an Arab diplomat who insisted on anonymity.

But several of its disclosures have proved accurate and have played a significant role in unearthing secret Iranian nuclear activities.

Katouzian has been involved in Iranian cultural and artistic activities in Britain.

The same rationale can be applied to the sanctions act because the United States is affected by Iranian terrorist activity.

But there is no consensus on the exact scale of Iranian activities.

Their most widely used chemical weapon was mustard gas, which paralyzed Iranian activity on the battlefield, and killed 700-1,800 immediately.

Iranian activities and policies constitute the major state-based threat to regional stability.

The officials, who declined to be identified, also reported increased Iranian naval activity in the strait.