"We are going to try to make certain that we understand the fact, that we understand the legal basis and we'll take the appropriate action," she said, responding to questions about the presence in Washington of Mohammad Nahavandian, who has a US green card and is economic advisor to the head Iranian negotiator on nuclear issues, Ali Larijani.

The US administration, which broke diplomatic relations with Iran in 1980, was alerted to situation by the media.

"You have someone with which the US does not actually have diplomatic relations but is a diplomat, a very high ranking diplomat in fact, inside the US," Rice said, calling the situation "anomalous".

The US State Department last week confirmed that the senior Iranian official was in Washington, but did not state how long he had been there or what he was doing.

The UN Security Council has given the Islamic republic until next Friday to halt its uranium enrichment activities, seen as the cover for a weapons drive. Iran has refused to comply with the demand.

The United States is pressing for UN sanctions such as freezes on the assets of Iranian leaders or travel restrictions. US President George W. Bush has also not ruled out taking military action.

Related Links
-