DOHA, Qatar — U.S. Secretary of State Hillary Rodham Clinton said today Iran is becoming a military dictatorship, a new U.S. accusation in the midst of rising tensions with Iran over its nuclear ambitions and crackdown on anti-government protesters.

Speaking to Arab students at Carnegie Mellon's Doha campus, Clinton said Iran's Revolutionary Guard Corps appears to have gained so much power it effectively is supplanting the government.

"Iran is moving toward a military dictatorship," she said. "That is our view."

Last week, the U.S. Treasury Department announced it was freezing the assets in U.S. jurisdictions of a Revolutionary Guard general and four subsidiaries of a previously penalized construction company he runs because of their alleged involvement in producing and spreading weapons of mass destruction.

The Revolutionary Guard has long been a pillar of Iran's regime as a force separate from the ordinary armed forces. The Guard now has a hand in every critical area, including missile development, oil resources, dam building, road construction, telecommunications and nuclear technology.

The U.S. is focused on gaining international support for sanctions "that will be particularly aimed at those enterprises controlled by the Revolutionary Guard, which we believe is in effect supplanting the government of Iran," she said.