According to department spokesperson Richard Boucher, "We just don't think it's wise to be investing in Iran's petroleum sector at this point when Iranian behaviour has still not changed in so many areas."

Boucher's remarks - whilst scathing in itself - went beyond the rhetorical when he announced that the US government was considering making use of a US statute to admonish firms that invested in one of the US's "Axis of Evil" countries.

According to Boucher, "The [US] government [will] look at the 1996 Iran-Libya Sanctions Act to see whether it can take action against companies investing in Iran. We do not encourage investment in Iran's petroleum sector [and] we have laws that affect our attitudes toward these investments."

"We will have to look at those laws appropriately," he said.

The reaction from the US government comes on the back of two deals that the Iranian government had recently signed with foreign multinationals to develop its oil and gas sector.

The first was the US$3 billion co-development project with a Japanese consortium to develop the Azadegan onshore oil field. The other was a deal with France's Total and Malaysia's Petronas forming a JV LNG company, Pars LNG, with the Iranian National Oil Co.