The Bush administration moved Tuesday to impose financial sanctions on Iranian officials and companies accused of helping the country develop nuclear weapons.

The action by the departments of State and Treasury marks the latest effort to tighten the financial noose on Iran, which the United States accuses of bankrolling terrorism and seeking a nuclear bomb.

Mohsen Fakhrizadeh-Mahabadi, a senior scientist at Iran's Ministry of Defense and Armed Forces Logistics, was among those targeted Tuesday.

"Iran's nuclear and missile firms hide behind an array of agents that transact business on their behalf," said Stuart Levey, the Treasury Department's under secretary for terrorism and financial intelligence.

Others targeted were: Yahya Rahim Safavi, a commander of the Iranian Revolutionary Guard Corps.; Dawood Agha-Jani, who is involved in Iran's nuclear program; Mohsen Hojati, involved in the country's ballistic missile program; Mehrdada Akhlaghi Ketabachi, the head of the Shahid Bakeri Industrial Group; and Naser Maleki, head of the Shahid Hemmat Industrial Group and an official in the Iranian defense ministry.

The action means that any bank accounts or financial assets found in the United States that belong to these people are frozen. Americans also are prohibited from doing business with them.

Despite three sets of U.N. sanctions, Iran has not only continued enriching uranium, but says it has expanded its program. Tehran's rising influence in the Mideast has emboldened it to reject a recent offer of economic incentives in exchange for giving up its enrichment program.

President Bush, attending a summit of world leaders in Japan, on Tuesday had yet to score even any small victories on getting Iran to stop enriching uranium.

The leaders' statement expressed "serious concern" about Iran's failure to meet world demands to stop enriching uranium. But it stressed the need to "resolve the issue innovatively through negotiation."

The departments' action Tuesday also covers the TAMAS Co. for its alleged involvement in enrichment-related activities and Shahid Sattari Industries.

The United States also imposed sanctions on three other entities believed to be owned or controlled by Iran's Defense Industries Organization, which was put on the U.S. blacklist last year. Those entities are Seventh of Tir, Ammunition and Metallurgy Industries Group and Parchin Chemical Industries.